GENUS TOXOEHYNCHITES 279 tuft of white, black, and orange hairs ; laterally are numerous white scales and white hairs in patches ; venter steel-blue. Legs metallic blue and purple ; ungues equal and simple.
Wings with some metalhc blue scales to the veins, as long or longer than the body.
280 CHAPTEK XII.
The Anophelina Sub-family.
This sub-family consists of but two genera, Anopheles and Cycloleppteron ; the latter of which, containing but one species, Cy. Grabhamii, Theob., has been separated from the rest of the sub-family by Mr. Theobald, on account of the peculiar character of its wing scales.
The characters of the sub-family may be briefly stated as follows : — Soberly tinted CuUcida, having their palpi of about the same length as the proboscis in both sexes ; and in which the larvae are unprovided with a respiratory syphon, the spiracles opening nearly flush with the general surface of the dorsum. The two genera may be distinguished as below: — Sub-family ANOPHELINA.
Veins of the wmgs furnished with scales arranged on the same general plan as in Culex, or in some cases, more nearly approaching to that of Tceniorhynchus.
Genus III. ANOPHELES, Meigen.
Veins of the wings ornamented with spots formed by large, round, deeply pigmented scales ; the ligliter portions being furnished witli long, curved scales, of lanceolate outline, and devoid of pigment. Genus IV. CYCLOLEPPTERON, Theobald.
In by far the majority of instances, the insects of this subfamily have spotted wings, and in even the few that are not decorated in this way, some tendency to exhibit this character of the group will be found to exist on close examination. As already mentioned, most of them have also the peculiarity of
THE ANOPHELINA SUB-FAMILY 281 posing themselves with the head pointing at the surface on which they are resting, and the abdomen elevated. Speaking generally, the gnats of this group are of moderate size, but one or two are a good deal above the average dimensionsof the family.
Possibly a third genus may have to be constituted for the reception of An. ocellatus, Theobald, on account of the dense tufts of peculiarly formed scales which fringe the posterior borders of the segments of the venter.
Genus III. ANOPHELES, Meigen (1818).
From an etiological point of view, the importance of this genus has been in no way impaired by the researches of the past year, as the number of proved cases in which its members have been convicted of serving as the intermediate host of the parasite of human malaria has steadily increased, and it has been further shown, by Capt. James, I. M.S., and also by Grassi and Noe, to bear a share in the transmission of filariasis. In the first edition thirty species of this genus were enumerated. Of these the notorious An. claviger (Fabr.), reappears as An. niacuhpennis, Meig. ; a name previously given as a synonym, as it appears doubtful if the insect referred to by Fabricius existed as a type in his collection. An. alhitarsis Arribdl., turns out to be but a synonym of the much less appro priately named An. argyrotarsis, Desv. ; An. musivus, Skuse one of An. annulipes, Walker ; and An. quadrimaculatus , Say, is the same as A7t. macidipennis , Meig. Of the rest, An. '^ sp. b.' mihi, for which the name '^ nigerrimus" was suggested; Aii amiularis, Wulp, with An. vanus, Walker ; An. pseicdopictus Grassi, and probably A71. pictus, Loew, are, I am inclined to think, nothing more than synonyms of An. Sinensis, Wied. ; as though Mr. Theobald accords them the dignity of ranking as sub species, they run so much into each other if any considerable series of specimens be examined, that the characters that separate them barely exceed the limits of variation, if at all. As Grassi's pseudopictus was treated as a synonym of Loew's pictus, this leaves twenty-four species, whose position at present remains unshaken. At the time of Mr. Theobald's monograph going to the press, fourteen new species had been received in the Museum and described by him, and I have found three more, quite distinct from these, in my own collection, which with one added description, the type of which has not been received, and three
282 GKATS OR MOSQUITOES — CHAPTER XII additional forms received while passing through the press, brings the total number of species enumerated in the present edition up to forty -six.
Besides these, several sub-species and varieties are described in the monograph, some of which appear to be fairly distinct, so that the total number of forms described in the present edition exceeds fifty.
The question as to whether a given form is really a distinct species or a mere variety, can only be settled by careful breeding out experiments, as nothing can fairly be considered a variety unless it can be shown that the eggs laid by a female produce some of the typical, and others of the variant individuals, and it is needless to say that we have no information of this kind whereby to settle the position of the various types of Anoplieletes described in the following pages.
On this account, the question whether some of those enumerated are or are not distinct, or sub-species, or varieties, is really one of a purely academical character, to which a far too great importance is sometimes attached, as for practical purposes it suffices if workers are supplied with convenient denominations whereby they can indicate the particular kind of insect to which their observations refer.
In the following pages accordingly, descriptions of all the various forms, whether ranked as species or varieties, are included, and the peculiarities of each are, with but one or two exceptions, further indicated by means of camera lucid a drawings of the wings and other characteristic portions of the insects. With the exception of figures of scales and tarsal claws, and other obviously much more highly magnified representations, all these figures are drawn at a uniform amplification of ten times the natural size, so that in measuring, centimetres may be read as millimetres ; though of course it must be understood that as Mosquitoes vary greatly in size in the same species, they can only be taken to refer to the actual specimen from which the particular figure was drawn.
This gives the great advantage of affording some idea of the relative size of the various species, but has resulted in some few of the smallest species being shown on a rather inconveniently small scale. As, however, the figures were originally drawn more than three times as large as they now appear, the use of a hand lens will be found to obviate this difficulty. The following is the amended definition of the genus according to the new classification.
THE ANOPHELINA SUB-FAMILY 283 ANOPHELES, Meigen (as restricted by Theobald).
"Characters of the Genus.— Head with both flat and narrow curved scales, but mainly covered with large upright forked scales {vide fig. 38) ; palpi long ha both sexes, usually about the length of the proboscis, 4-jointed m the $, 3-jointed m the ^,but constrictions at the base apparently make the $ 5 or 6-jointed and the (3^ 4 or 5-jomted ; in the ^ the last two joints are short, thick, and often ohve-shaped. Antennge 14-iointed, filiform, pilose in the 2 , plumose in the <? , and 15-jointed.
" Thorax sometimes nude on the dorsum, usually with narrow curved or small spuadle-shaped flat scales. Abdomen generally pilose, but sometimes with a few scales, and rarely with many {A. Pliaroensis, milii). Wings covered with small scales of normal form or inflated, with the first sub-marginal cell longer and narrower than the second posterior cell ; both the second and third long veins run past the cross-veins into the basal cells, a character which I have noticed very marked in all species examined." — (Monog. I, p. 115.)
Another character, the importance of which was originally pointed out in the first edition, and which the examination of the large accumulation of new material has shown to be of thoroughly generic value, is that both fork-cells appear to be uniformly smaller, and with longer stems in the male than in the female. In the female the anterior fork-cell is usually distinctly longer, though narrower, than the posterior, but in the male the anterior is seldom longer than the posterior, and is in some cases of dimensions almost recalling those of the wing in Megarhina.
The arrangement of the scales of the wing-veins, though essentially of the Gulex type, often recalls that of Taniorhynchus in its general appearance, being much denser than is usually the case in the former genus ; for though the linear scales are not broad and round at the end, as in the later, they are usually broader than in Gulex, and of a lanceolate outline (pi. xi, figs. 5a, h, c, d), in place of being narrower and square-ended. The genus is very widely distributed, though individual species rarely are spread over as wide an area as some Culices, and taken generically, they do not extend into as high latitudes as Gulex. Apart from these limitations, I believe that a map of the world, coloured to show localities in which they are found, would, if the truth were known, show well nigh the entire habitable globe of that tint, and that the many gaps in the existing map of the monograph really show that we know little on this point about these localities.
284 GNATS OR MOSQUITOES — CHAPTER XII As already pointed out, malaria is limited not entirely by the existence or otherwise of Anopheletes, but also absolutely by conditions of climate outside which the parasite is unable to live ; but the large material now to hand shows that where climate is suitable, Anopheletes and malaria are generally found together. On this point Mr. Theobald, in the Monograph, writes : — "Professor Nuttall tells me that in England the distribution of A. niaculipennis and A. hifurcahcs compares exactly with the old distribution of ague. At the same time Anopheles occur in districts where no ague has existed.
" In those countries where malarial fever is rife the collections of Mosquitoes received by the Museum have always contained many Anopheles, with one notable exception, namely Victoria. For instance, they occur in very large numbers on the West Coast of Africa, in Central Africa, in large numbers in the Malay Peninsula, in the West Indies, and in India. On the other hand, in such parts as Brazil and the Ai-gentine, even along the swampy borders of the large rivers, malaria is not very prevalent. Anopheles here, as far as observations go, and records that I can find, are far from common, although other Mosquitoes are a great scourge.
" It does not of course follow because Anopiheles are present that malaria is present, but where the latter occurs Anopheles have in all cases but one been shown to exist in numbers. Amongst the small collection of Mosquitoes sent froin Victoria no Anopheles are included, but a series of Culex tceniatiis bears a label, ' abundant in the malarious districts of the ujalands of Victoria.' Four species of Anopheles, however, occur in Australia, and may have been overlooked in this colony, particularly as the collection only contains three species, which number would probably be greatly increased on a further examination of the district. From Mauritius, where malaria is rife, tlie collecttion only contained a few poor specimens of Culex, but three species of Anopheles occur in abundance, one species particularly along the coast, where the fever is most prevalent."
A good deal has been written as to whether the bite of these Mosquitoes is painless or otherwise, and as to whether they " sing " or not, the opinions expressed being most contradictory. That Anopheletes " sing " I think there can be no doubt, for the simple reason that the sound made by Mosquitoes of all sorts is due to no voluntary effort of any sort on the part of the insect, but is an inevitable, though accidental, necessity of the fact, that owing to the peculiar character of their flight, their wings are kept vibrating at a certain number of strokes a second, and hence must produce the musical note corresponding to it. Where, as in most of the larger insects, this rate is a low one, we hear the
THE ANOPHELINA SUB-FAMILY 285 " insects' drowsy hum " of the popular lyricist, while the rapidly vibrating wings of the smaller fry cannot but make a " shrill pipe." That we hear more of this in the case of Mosquitoes than in most other smaller insects, is due to the fact that the affection they entertain for us leads them to hover close to our ears preparatory to imprinting the tokens of their regard that we have such strong reasons for avoiding ; reasons which render us particularly alert to the sound.
Personally, I am inclined to think that the bite of Anopheles is neither more nor less irritating than that of other Mosquitoes, and that the differences of opinion on this point are due to the varying degree of immunity which all, more or less, acquire ; and also to the circumstance that any specially virulent effects are usually due, not to the venom of the Mosquito itself, but to accidental impurities introduced along with it. I have again and again seen middle-aged Indians, who had long lost all power of reacting to the pure salivary secretion of Mosquitoes, actually apply for treatment an account of their faces being so swollen that they could scarcely open their eyes, and the fact that such cases are specially apt to occur among patients lying in a surgical ward makes it probable that the unusual effect of the bites is in such cases due to the Mosquitoes having indulged in a previous feed from some wound secretion. Occasionally the swelling in such cases has an erysipelatous character, and I have met with suppuration ; but as a rule, it subsides in a day or two.
In the same way, it may be doubted if it is safe to generalise on the supposed preference of Mosquitoes for the blood of any particular variety of the human race.
That they should be able to follow up the trail of an adult "buck nigger" more readily than that of the well-groomed European can be easily understood, without assuming that Mosquitoes find Kru-boy tastes nicer than Englishman ; and in India, where the personal habits of the indigenous population are more cleanly than those of the "West African, one hears nothing of such preference. In any case, however, the number of Mosquitoes of any given species may vary so greatly on consecutive days of the same week, owing probably to differences in the state of the atmosphere, that something more than a few desultory observations are required to justify the expression of any opinion on the point.
The identificafcion of the various species in this genus is rendered none the easier by the fact that most of the most
286 GNATS OR MOSQUITOES— CHAPTER XII prominent specific characters vary a good deal, so that it is usually possible to find aberrant specimens of any one species which more or less resemble those near it ; and an extension of the kind of argument used to deprecate the so-called " multiplication of species " might easily be made to reduce them to absurdity by showing that in this way the whole genus, or family, if it comes to that, is but a single species ; but in spite of this, where we find Mosquitoes presenting given characters, which run fairly true through a long series of individuals ; it is certainly more convenient to regard them as distinct than to confuse our ideas by the enumeration of the endless catalogue of possible variations that must be appended to specific definitions in any attempt to cut down the nominal number of species. There is hardly any character relied upon in systematic work that does not vary considerably in Mosquitoes, and the value even of anatomical characters cannot be pushed too far, as the relative positions of the longitudinal junctions of the longitudinal veins, and the distance apart of the transverse veins, which are often recorded at great length in many descriptions, often vary so much that they would better be left unrecorded. The general relative position of the transverse veins with respect to each other indeed does not, so far as can be made out, vary, so that we shall not find the posterior, e.g., sometimes internal, and at others external, to the middle transverse ; but their distance apart, as may be seen in the figures of two specimens of Grassi's jpseudopictus, $ , plate viii, figs, lib, lie, varies so greatly in the same species that it is quite useless to record such points, unless found constant in a long series of specimens ; but the position of the cross-veins with respect to each other, though not their proportional length or distance apart, is of considerable value in distinguishing species, and is given, for ready reference, in tabular form on following pages.
In this table, and elsewhere, for the sake of brevity the mathematical sign for parallel, " ||," is used to signify " opposite," or "in one line with " ; and where 3 (the middle transverse vein) is placed external to the other two venules^ the arrangement is stated as "alternate"; where, on the other hand, they are placed like the steps of a stairway, 2 (the supernumerary) being placed outermost, and 4 (the posterior) innermost, it is given as " seriatim."
Coquillett, I understand, doubts if even the form of the tarsal claws is constant, but the larvae of allied species are so often found associated in one puddle that it may be suspected that the