TESTUDO VICINA. (i) The description of the skeleton of so young an individual could hardly be accompanied by important results as regards the object of this work, and is therefore omitted. Caudalvertebre24. 3.
'TESTUDO VICINA. This race was described by me in the Phil. Trans. 1875, p. 277, from the carapace and skeleton of an adult male example, formerly in the possession of Prof. Hux.ey, and now in the British Museum *. The history of that specimen is lost; but, from Commander Cookson’s observations (Proc. Zool. Soc. 1876, p. 524), it seems to be very probable that Albemarle, the largest of the Galapagos Islands, is inhabited by at least two distinct races, and that 7. vicina is one of them, viz. that of South Albemarle. Having found at the S.W. end, near to Iguana Cove, a Tortoise differing in shape and general appearance from those captured near Tagus Cove (North Albemarle), the shell being deeply striated, and not smooth as is the case in the latter, he remarks :— . “T suppose that abundance or variety of food would be sufficient to produce this difference of appearance in the tortoises from different localities in Albemarle Island, this part of the island, the 8.W. end, having a comparatively luxuriant vegetation, whereas the neighbourhood of Tagus Cove is described by Mr. Darwin as being miserably sterile; but it is a point not to be overlooked that these two localities are separated by a coast-line of 70 miles, and that between them lie three of the highest volcanic peaks of the whole group, one if not two of which have been active until quite recently; and from the flanks of all three, streams of black lava descend, each several miles in width. Again, the most northern of these craters is situated almost in the centre of the narrowest part of the island, and sends down its black streams in all directions. ... I think one may conclude that these lava-streams are quite impassable to the Tortoises, and that, as far as these creatures are concerned, the north and south ends of the island are as effectually separated as they would be by a channel of 40 or 50 miles of deep water.” At the same place where that living specimen was found, Commander Cookson picked up the skull (without mandible) of what was said to be the largest Tortoise seen * My endeavours to trace in the various collections the specimens which are known to haye reached England alive within the last forty years have been hitherto singularly unsuccessful; and the present example is the only one which may be supposed to be possibly identical with the individual reported to have been sent to the ZoologicalSocietyin1834,bytheHon.ByronCary,fromtheGalapagos(Proc.Zool.Soc.1834,p.113). That specimen is said to have weighed 187 1b., and measured in length, over the curve of the dorsal shell, 443 inches(Ifindinourspecimen414inches),andalongthesternum25}inches(asinours);itsgirthroundthe middle was 754 inches (69 inches according to my measurement). It is added that “the lateral compression oftheanteriorpartofthedorsalshell,andtheelevationofitsfrontmargin...areinthisspecimenstrongly marked.” ft This specimen, unfortunately, is one of those lost in transit to England.
74 THE RACES OF THE GALAPAGOS.
for twelve or fifteen years. It is 5} inches long (to occipital condyle), and agrees in every respect with those from North Albemarle; and as the skulls of all these Albemarle Tortoises are perfectly identical with that of the specimen received from Prof. Hx ey, which externally differs from the North-Albemarle form by the deep striation of the scutes, we may reasonably infer that this 7. vicina is actually the race of the southern part of the island.
The form of the carapace (Plate XXXII. fig. A) reminds us of that of 7. elephantopus ; but it is still more depressed, the greater part of the two middle costal plates participating in the formation of the plane surface of the back. The first dorsal scute is but very slightly declivous towards the front ; and the edge of the shell along the three anterior marginals is reverted and scalloped: thus the fore part of the shell has in a slight degree the form of a saddle; but it is much less compressed than in 7. ephippium or abingdontt. ‘The striz of the plates are very distinct, but shallow, and distant from one another (broad), occupying the greater part of the surface of each plate. The striated portions of the plates are not of the same intense black as the smooth ones, but more or less tinged with brown. The shape of the sternwm differs from that of the preceding species, its gular portion being singularly constricted and having the lateral margins excised. The gular plates are truncated in front. The opposite end of the sternum is dilated, the caudal plates being expanded like wings; their hind margins meet at an obtuse angle. All the plates of the sternum, with the exception of the pectorals and abdominals, are striated, like the dorsal plates. The surface of the sternum isdeeplyconcave.
There is in the British Museum a young stuffed example, with a carapace 124 inches long (without particular indication of its origin), which I am inclined to refer to this species. It has the same depressed shell as the adult, with a similar striation of the plates, and with the anterior margins distinctly reverted; but the sternum is not constricted anteriorly, nor are the caudals expanded like wings. At present we have not the means of judging whether this difference could be accounted for by age or sex; however, as the skull of this young individual agrees singularly well with that of the adult, there is good reason for believing it to be a second example of the same species. The measurements of the two specimens are as follows :— Length of carapace. Width of carapace. Depth of Sternum. Caudal plate. In str.line. Over curve. Instr.line. Overcurve. carapace. Length. Width. Length. Width. Spec. in. in, in. in. in. in. in, in. in.
Ad. 3... 38 413 25 42 16 254 24 44 63 Young... 123 144 9 144 54 104 84 1} 23 The skull is so similar to that of 7. microphyes that it may be noticed in connexion withthatspecies.
Cervical vertebre.—On comparing the neck-vertebre of J. vicina with those of 7. elephantopus, we find them generally to be somewhat less slender, and with the crests
TESTUDO VICINA. 75 and ridges less developed; otherwise they are formed according to the same type, and the first, seventh, and eighth are the only vertebree which exhibit peculiarities indicative of specific distinctness. In the atlas (Plate XLVI. fig. B) the lateral portion of the neural arch is but little constricted, at least as wide as the broad zygapophysis, which is longer than that part of the bone which forms the roof of the neural arch. In the seventh vertebra (Plate XLVII. fig. C) the summit (a) of the neural crest is not single, as in the other species, but split into two prominences, separated from each other by adeep notch. In the eighth vertebra the hzemal crest is produced forward to the level of the anterior articular surface, and almost hamate in form, whilst it does not extend beyond the middle third of the length of the centrum in 7. elephantopus. Measurements of cervical vertebra :— 2nd, 3rd. Ath. 5th. 6th. 7th.
millim.millim.millim.millim.millim.millim.
emereomCenmiruniyetamivecatasheeuupevanacesatonneeveaden«A76588808272 Wepthrormiddle Ol CONG ci..cospracnpeisnincdes Sacer sess 34 26 25 26 25 49 Horizontal width of middle of centrum .................. 14 18 17 20 25 27 Wadthrot anterior Condyle: sicésisisececuyccndeuess .ceeees 15 18 20 ee oe aah Width of anterior articular cavity ....... Uicbenasene beeck wis vei Rvs 36 42 4] Witdtheot POSLETION CONGYIE s.5.6i. css. cece sied vod cea seanad mei sae 25 28 39 re Wadth of posterior articular cavity...........0ccssseseeees 19 23 =< in ve 50 Distance of outer margins of anterior zygapophyses... 20 33 38 37 4.2 33 Distance of outer margins of posterior zygapophyses... 28 31 31 35 28 55 Dorsal vertebre.—The last of the three vertebree which emit pleurapophyses to form the protuberance for the articulation of the ilium is the eleventh; so that only eleven vertebra can be assigned to this part of the vertebral column. Of the two heads into which the first rib bifurcates, the posterior is more slender than the anterior; the triangular space enclosed by them is wide, but less so than in 7. elephantopus. For comparison with the latter species I give the length of the centra of the several dorsal vertebrae :— Dorsal vertebre .... Ist. 2nd. 3rd. 4th. Sth. 6th. 7th. 8th. 9th. 10th. 11th. 12th. mm. mm, mm. mm. mm. mm. mm. mm. mm. mm mm mm.
Test. elephantopus......... 65 80 80 80 78 55 48 48 16 14 I16— 22 WCSUMUICING a aecsratewes eas 00, §o0° 6/87" (79 61 43 932 Iv “15. 18> (2)) Caudal vertebre twenty in number ; but it is possible that the last rudimentary ossicle hasbeenlost.
Limb-bones.—Singularly enough, the resemblance which we notice between the skulls of this species and 7’. ephippium does not uniformly extend to the other parts of the skeleton, the limb-bones of 7. vicina being much shorter and stouter than in that species, approaching more 7’. elephantopus. 'The scapulary (Plate LIV. figs. C, C’) especially is stout and massive. ‘The angle at which the scapula and acromium meet L2
76 THE RACES OF THE GALAPAGOS.
is much less obtuse than in TZ. elephantopus (about 100°); the body of the scapula is compressed, elliptical, with both its anterior and posterior sides equally convex; a transverse section through its middle would be represented by the figure of a greatly elongate O. ‘The shaft of the acromium is trihedral, with the edges rounded, and with the extremity compressed and slightly dilated. The coracoid is not ankylosed to the scapula ; and its proximal part (neck) is singularly dilated, and very much broader than the corresponding part in 7. elephantopus. In fact the differences in the scapularies of | these two species are so great, that they alone would clearly prove their specific distinctness.
T.clephantopus,T.vicina, 790 millims.
long.
840 millims.
long.
millim. millim.
Length of scapula (measured from the coracoid suture) ... 200 188 Circumference in the middle of the shaft ..................... 75 75 Longitudinal diameter of glenoid cavity ................000. SOO 55 uength, of coracoid — .0.5. cicastutuncettstentces saan eee ee eee 86 83 Greatest. width! of coracoid’ =e i..scesw chee) eee eee ee 70 74 east width.of neck of coracoid®>....2-.-se-eteceeenine ceeeee 20 33 DHength of acromatin acca, corcucu.cnn entero een ee EERE 84 78 The humerus is so similar to that of 7. elephantopus (and consequently very dissimilar to that of 7. ephippiwm) that no detailed description is needed; but, as in the latter species, the canal for the blood-vessels on the radial edge, close to the elbowjoint, is deep and partly open.
T.elephantopus.T.ephippium.T.vicina.
millim. millim. niillim.
length ofhumerusind. peice. eee erence 216 235 225 Circumference of the narrowest part of shaft 89 91 95 Longest diameter of the head .................. 40 40 40 Shortest diameter of the head .................. 37 35 38 Extreme breadth between the condyles ...... 82 82 81 The bones of the forearm (Plate LIV. fig. D) are also shorter than those of 7’. ephippium, more similar to those of 7’. elephantopus, particularly with regard to the deeply emarginate radial edge of the wlxa. Both bones are smooth, without prominent ridges or tuberosities. The ulna is twisted round its longitudinal axis, so that the transverse diameters of its proximal and distal dilatations would intersect each other at an angle of about 45°. The olecranon is not much developed. The articular facet of the radius for the articulation of the humerus is a rectangular triangle, with the point directed backwards, and the shortest side in front.
TESTUDO VICINA. | vi T. elephantopus, T. ephippium, T. vicina, 790 millims.
long.
840 millims.
long.
840 millims.
long.
millim. millim. millim.
Heme thro telmmree nt sa tctne dene st eonscnecons nos 137 155 137 WACasteWACEMWOUgULMA,Whe:.0sscvishlelaascansCntadiaineeen282626 Menet hyo nadMase. ey, cis diissdene due sutees vt. cdantle 121 149 122 Least circumference of radius ...................55 50 51 49 Carpus.—The coalescence of the scaphoid and intermedium, and of the two radial ossicles of the third series, which we have found complete in 1’. elephantopus, has commenced in the present individual; but the lines of separation are still clearly visible.
The pelvis differs from that of 7. elephantopus in the same manner as does that of T. ephippium; but its horizontal diameter is comparatively greater than in either of those two species. All the sutures are present. T. elephantopus, T. ephippium, T. vicina, 790 millims.
long.
840 millims.
long.
840 millims.
long.
millim. millim. millim.
Longest inner vertical diameter of pelvis............ 170 160 157 Longest inner horizontal diameter of pelvis ...... 182 118 144 Shortest inner horizontal diameter of pelvis ...... 112 97 97 Longest diameter of foramen obturatorium......... 42 42 38 Whadthrof symphysial bridge .........s60cc0slevte senses 26 35 4] Wepthrot symphysial bridge ...0....0s sce cssweee 26 23 26 Least breadth of posterior portion of ossa ischii... 61 80 76 Cre CHEOMOS: WIG Ceavivinrcasescied~ seals tentna won ttoasa es 140 130 134 Weasteoreagt ha Gf OS) 7) caicec sacs seswceeercaaeeranins 30 27 29 The femur agrees almost entirely with that of 7. elephantopus, thus differing from that of 7. ephippiwm in the same points, which will be indicated in the description of the latter species. The bones of the /ower leg and tarsus do not show any noteworthy peculiarity, the state of coalescence of the astragalus and calcaneum being the same as in some of the carpal bones mentioned above. T.elephantopus,T'.ephippium,LT.vieind, 790 millims.long.
840 millims.
long.
840 millims.
long.
millim. millim. millim.
MGEMStNOtCROeCHAUAiypack.hanamesnstaevinncwlonsayaxles169186165 Least circumference of the femur.........,.........+. 80 90 79 Wadthi of thetcondyles) 00s... ccciyeced esterase nes eyes 66 67 73 Meng uny ote thortilbiann, &.0.0e.s sekves ae 1deend s aakewe 136 150 129 Least circumference of the tibia ...................65 60 72 57 Menothr otter ala tos. .u%.inseavetenssesseh.. accuses cle 123 138 123 Least circumference of the fibula ..................... 45 45 43
78 THE RACES OF THE GALAPAGOS.
4, TESTUDO MICROPHYES.
This race was described by me in Phil. Trans. 1875, p. 275, from a specimen 224 inches long, then lent to me by the Museum Committee of the Royal Institution of Liverpool, but since acquired by the Trustees of the British Museum. In that original description I stated that it was a fully adult male, drawing this inference from the concavity of its sternum—and suggested, moreover, that the specimen, on account of its small size, might be the Hood’s-Island race of Porter. The specimens collected by Commander Cookson in North Albemarle prove at least the first of these views to have been erroneous, the typical specimen being undoubtedly a female. In this species, and perhaps also in the other flat-headed Tortoises, the sternum of the adult female is conspicuously concave, much more so than in males of the same size, though not of the same age. The concavity of the sternum of females extends over a greater portion of the surface of the bone than in the males (in which it is deepest behind the middle), and never attains the same degree of depth; also the sides of the sternum and the caudal extremity never become swollen and callous. Commander Cookson obtained his specimens near to Tagus Cove, about 4 miles inland, on a small elevated plateau covered with stunted bush and high, very coarse grass. Of twenty-four examples of all ages the following reached England * :— A. Adult male, living; carapace 353 in. long (in a straight line); weight 240 Ib. B. Adult male, shell, skull, and skin of legs; carapace 33% in. long. C. Haif-grown male, shell, skull, and skin of legs; carapace 25 in. long. D. Young male, living; carapace 164 in. long. Brought home on board the ‘ Challenger.’
EK. Adult female, living; carapace 27 in. long. I’, Adult female, living; carapace 253 in. long. Brought home on board the ‘ Challenger.’
G. A very young specimen, living; carapace 18 in. long. A very great advantage has been gained by Commander Cookson bringing home several individuals from the same locality, thus enabling us to discriminate between specific characters and other modifications due to various causes. And it was important to ascertain that there is no variation whatever either in the three skulls from Albemarle Island or in those from Abingdon, and that, likewise, the carapaces from the same island differed only in those points which I have always considered to be due to sex or subject to change with the progress of growth. As long as the Tortoises are young, growth, as far as it is externally visible, proceeds along the margins of all the scutes; the sutures get broader, appearing as whitish seams, soft and very sensitive. After some time the young portion of the epidermis * The living specimens have been temporarily deposited in the Zoological Gardens; two were put by Commander Cookson on board the ‘ Challenger.’
TESTUDO MICROPHYES. 79 becomes horny, and is raised in a line (stria) running along each side of the suture. At a later period this increment takes place only (or, at least, only conspicuously) in certain portions of the carapace. ‘Thus, in those species in which the male is distinguished from the female by a saddle-like compression of the front portion, the sutures between the first two costals and the corresponding marginals and pectoral widen, the change in the form of the carapace being almost entirely confined to this portion. It is impossible to say at what period growth ceases in these animals; probably it greatly varies in different individuals. The gigantic specimen of Testudo elephantina, which I observed in a living state, and which was certainly 100 years old, if not more, was still growing at the time of its death; but the outward signs of the increment of the shell were confined to the upper and lower margins of the lateral marginal scutes; and the animal may have gained thereby an increase of one inch in the circumference of its carapace within the periodofayear.
Description of the Male.—In one of the largest male specimens (A, 33} inches) (Plates XXXIV. & XXXYV. fig. A) the shell is moderately depressed, with the upper surface flattened, the upper profile from the centre of the fourth vertebral scute being nearly straight. However, the central line of the first vertebral, which is raised into a slight ridge, gently slopes downwards towards the front. Each side of the fore part of the carapace is deeply concave; but the margins are but slightly reverted and scarcely scalloped. The part of the shell above the hind legs is bulged outwards, especially towards the margin, all this reminding us of that peculiar form of shell which we find fully developed in the Charles and Abingdon, and in one of the Aldabra Tortoises. The declivity of the last vertebral and caudal is very steep; and the latter scute is slightly bent inwards. The entire surface of the carapace is irregularly pitted from the unequal development of the osseous substance ; and nearly every trace of striation has disappeared. The two front marginal scutes join each other bya very short suture. The colour is a dark horn-colour, almost black.
The head, of which I give a full-size figure, in comparison with that of 7. elephantina (Plates XXXII. & XXXIIL), is comparatively much larger than in the latter species, and can be held nearly at a right angle to the perpendicular neck; the animal is able to turn it aside sufficiently to look at objects behind it. The neck is often held erect, raised high above the carapace, but seems to be not quite so long as in the Abingdon Tortoise.
In the second large male specimen (B, 33} in. long), the shell is somewhat less depressed, the areolar centres of the three middle vertebrals being distinctly raised ; and the upper profile slopes downwards from the centre of the second vertebral towards the front. The sides of the fore part of the carapace are less concave; a deep indentation between the first and second marginals. ‘The posterior declivity of the shell is very steep from the very projecting areolar centre of the penultimate vertebral. The surface of this carapace is very smooth, with only a few shallow pits. Sternum deeply concave,
80 THE RACES OF THE GALAPAGOS.
with short and broad anterior and posterior lobes, and truncated in front and behind.
In a half-grown male (C, 25 in. long) (Plate XX XVIII.) the reversion of the margins is only slightly indicated. The striation occupies a broad band round the periphery of each scute; but the strie are very superficial. The concavity of the sternum is very shallow; and there is a very open indentation on the hind margin of the caudal scutes. Description of the Female (Plate XXXYV. fig. A, and Plates XXXVI. & XXXVIL.). —The carapace is more depressed than in the male; and the upper profile slopes from the middle towards the front, being quite a steep decline along the first vertebral scute. There is scarcely any concavity on the sides of the fore part of the carapace; and the part of the shell above the hind legs is but slightly bulged outwards. The two front marginal scutes join each other by a much longer suture than in the male. The caudal plate is distinctly turned outwards. Sternum slightly concave, and caudal margin somewhat indented, as in the half-grown male specimen (C). The surface of the carapace is pitted, without any trace of strie. Tail very short (only 2 inches long). In the typical specimen (Plate XXXVII.), which, as mentioned above, is likewise a female, the plates are not pitted, and the sternum is truncated behind. Asa (probably) individual peculiarity must be noticed the confluence of the two anterior marginals into one plate on each side.
The females erect their neck much less frequently, and never to the same extent as the males; whether the vertebrae themselves are comparatively shorter than in the male cannot be ascertained for the present.
Very young specimens (up to 16 inches in length) show a very well-marked striation of the whole surface of the scutes, the areola alone excepted, and cannot be distinguished from the young of other species.
Measurements.
Spec. typ., 9. A, d. 1B fe Oh he E, @.
in. in. 1n. 1n. 1n.
Length of carapace in straight line ...... 224 333 B35 25 27 Length of carapace over curvature ......... 26 44. 4] 324 35 Width of carapace in straightline ......... 153 25 244 193 22 Width of carapace over curvature ......... 29 46 42 345 38 Menotheotisternum ay)... eee ees 18 274 244 204 214 Wadthsoftsternum’s,...e4:.e eee ee 14 25 23 164 20 Wadth*of posteular plates) 7))22).-2)-2. 8 14. 12 10 10 Length of posteular plates...) 4.94.0). 44 9 6 5 6 Jheneth-ofscaudaliplate 54...) epee 2 44 33 3 43 Width of;caudal:plates....-9..-.2.0e eee 33 8 63 32 23 Skull (Plate XLV. figs. A-C, g; Plates XLII.-XLIV. fig. B, ¢).—The principal differences in the skulls of the Galapagos Tortoises are found in the palate and lower