CHARACTERISTICS OF MAMMALS 9 Some families contain only one living genus, the next lower step in classification. Man belongs to the Genus Homo. With the exception of the larger and more striking mammals, treatments in this book are confined to the genus. Most genera are easily recognizable. Many species, on the contrary, can be dis- Porcupines Rats Squirrels Monkeys (Primates) Flying Lemur Insect Eaters (Insectivores) Hoofed Mammals Elephant Pouched Mammals (Marsupials) Rabbits Scaly Anteater Flesheaters (Carnivores) Seals Whales and Porpoises Egg-laying Mammals Primitive Extinct Mammals Fig. 3 — Generalized diagram of the mammalian ''Family tree^* tinguished only with difficulty. This handbook would be unwieldy were it to attempt to give descriptions of every species in each genus. The species to which man belongs is Homo sapiens. Homo, the generic name, in Latin means "man"; sapiens, the specific name, means "wise." Linnaeus, the founder
10 MAMMALS OF THE PACIFIC WORLD of scientific classification and nomenclature, gave man this name.
The scientific name of a species always consists of two words : the first or generic name, analogous to a surname, begins with a capital letter; the second or specific name, equivalent to a Christian name, in Zoology begins with a small letter. Scientific names should be printed in italics.
In technical work races or geographic varieties, called subspecies, are often recognized. A third Latin name is added to the specific name of a new variety, and the second name of the variety originally described is repeated. Man is divided into several races; the white race bears the scientific name Homo sapiens sapiens. In this handbook little attention except in the monkeys is paid to such races because of limitations of time and size. But the idea underlies much of the discussion. Finally we come to that indivisible element, the individual. Just as no two people are entirely alike, and as a human race contains many diverse individuals, so wild mammals vary individually; no two are precisely alike. This individual variation has been appreciated only recently, and its study is a difiicult and lengthy task. Only by accumulating large numbers of specimens can it be solved, which is one reason why many of the mammals described here are of doubtful status — why we do not always yet know whether they are actual species, races, or merely individual variants.
Measurements of mammals in scientific and foreign books and articles are usually given in units of the metric system, commonly in millimeters. In this book, for the convenience of those who do not readily estimate size in this more efficient system, inches, feet, and yards are used. To find the metric equivalents, inches are multiplied by 25 to give millimeters.
Species of Mammals of the Pacific Area Egg-laying Mammals: Duckbills, Spiny Anteaters. Order IMonotremata Only in Australia and New Guinea are there mammals that lay eggs and suckle their young. They are of two main types: the velvet-coated Duckbill or Platypus, and the Spiny Anteaters or Echidnas.
The Duckbill. Family Ornithorhynchid^ The Duckbill or Platypus (Ornithorhynchus) , though humorously described as half bird and half animal, is nevertheless a true mammal. The jaws and front of the face project as a rubbery or horny duck-like "bill" and are covered with hairless, tough skin. The bill is made to appear more duck-like by the lack of teeth. However, in unborn duckbills teeth are present. These are lost during development.
The fur of the duckbill is close and velvety, and colored dark grayish brown. It shows the sheen commonly observed on other aquatic animals such as otters and Australian water rats. The tail is relatively short and stumpy. The feet are webbed for swimming and the hind foot of the male bears a horny spur, at the base of which is a gland containing a poisonous secretion. Very young females also have spurs which, however, become atrophied soon after the body length exceeds nine inches. Males are much larger than females. The total length of males is twenty-four inches, and of females eighteen inches, the tail of each being about one-fourth of the total length. The food consists of snails, aquatic larvae, worms and cray- 11
12 MAMMALS OF THE PACIFIC WOELD fish mixed with mud. Long burrows are made in the banks of rivers, usually with two entrances — one of them below water. The nest, made of grass, leaves, rootlets, and reeds, is placed in an enlarged chamber at the inner end of the burrow. Usually two or three eggs are laid, which are about seven-tenths of an inch in length and only slightly less in diameter. The eggs have horny white shells and become stuck together by means of a sticky substance with which they are coated. It is estimated that they hatch through the warmth of the mother's body in about two weeks. The newly hatched young have not developed the "duckbill" but have a hard, sharp process or "caruncle" on the muzzle. They are said not to nurse for nearly a week. After that the mother secretes milk through two milk patches (not nipples), wetting the hairs thereon, which the young suck. Scratching with their caruncles by the young is thought to start the mother's milk flowing.
Recently important new facts concerning the life habits of the platypus have come to hand.^ These relate to a mother and a young one bred at Badger Creek Sanctuary, Healesville, Victoria, Australia. In the non-breeding season the platypus spends a very large part of the twenty-four-hour day seeking food at the bottom of its swimming tank. It eats enormous amounts of animal food, the quantity of which probably rises to a peak when it is nursing its young. At that time, in the Sanctuary, a single night's food (which incidentally cost about five dollars per day) comprised four hundred large earthworms, three hundred and thirty-eight beetle grubs, and thirty-eight small crayfish. The total weight of that food was one and threefourths pounds. Since the maximum live weight of the animal was only two pounds, digestion must have taken place almost concurrently with feeding. Maintenance of extreme activity — swimming, digging, and giving of milk to the young platypus — requires relatively very large amounts of that easily assimilable vital fuel.
^ Fleay, D., 1944, Animal Kingdom, New York, 47, pp. 61-69.
SPECIES OF MAMMALS OF THE PACIFIC AREA 13 When not seeking food the animals are active making or altering the long earthen burrows which they mine in the banks of streams. The building of the nest which will contain the eggs and young takes place about twelve days after mating, in October. To prevent shrinkage the eggs must be kept in a saturated atmosphere. Quantities of leaves and grass, soaked in the water, are gathered together, then wadded into tight packets beneath the tail, and so are carried to an enlarged nest chamber at the end of one of the tunnels. A series of earthen plugs is maintained between the nest chamber and the several outlets. They are believed to keep the atmosphere of the chamber moist by checking air movements. Nest building is a strictly "business" affair. When working at it the mother practically stops feeding; she completes nest construction with the water-soaked leaves in some eighteen hours. The first egg is apparently laid within a day or two, the developmental period of the egg within the mother's body having lasted about fifteen days. Incubation of the eggs requires some nine to ten days more. During that time the mother platypus remains in her burrow for periods of several days at a time. She eats little or nothing and emerges merely to defecate. After the hatching of the eggs the mother reverses her time-table; she again spends many hours in the water feeding ravenously, and between times retires to the burrow to feed the babies. For the first few days after the eggs have hatched the mother seems to secrete no milk. During that time she scratches the mammary area of her body a great deal, which activity possibly helps to induce her milk to flow. She does not wean her young until they are about four months old and nearly as large as herself. At approximately that time the mother develops a fine new coat of glossy fur. The baby platypus is a singularly helpless creature, quite as helpless as a human baby. It remains unable to crawl until it has grown almost as large as its parent, the only movements of its limbs being feeble scratching efforts. It is nursed by the mother until it is almost fully grown and has attained the weight
14 MAMMALS OF THE PACIFIC WORLD of one pound. Until it is more than two months old it seems unable to maintain its body heat ; the skin becomes cold when the mother is away from it. At two months the body length is only nine inches, the eyes are still unopened, the beak is short, the fur barely developing. At three months, the body length is thirteen inches, the eyes are fully open and alert, the bill straight but still short, and the fur well developed except on the tail. The animal can utter a shrill growl. Movement is still uncertain and slow. At three and one-half months the body length is thirteen and one-half inches, and the young animal can crawl better. And at four months, although the body has grown no longer, the baby can crawl actively and come out from the burrow to the water for its first swim and first food not provided by its mother. In the wild state where conditions are less favorable for the mother, the babies may be forced to leave the nest somewhat earlier, when they are smaller and less able to fend for themselves.
Spiny Anteaters. Family Tachyglossid^ These are heavy-bodied animals with the skins covered with short, sharp spines mixed with hairs. They are almost tailless, and with a snout so much elongated that they look like large, beaked hedgehogs. Teeth are absent at all stages of development. The eggs are carried and hatched in the pouch, not placed in a nest as is done by the platypus.
The Straight-beaked Spiny Anteater {Tachyglossus) has a nearly bare snout, which is used for rooting and digging in soft soil. The legs are powerful; the feet are furnished with long digging claws, with which the animals can bury themselves in the ground with astonishing speed. But it is stated that they do not make tunnel-like burrows. Their color is brownish gray with basal parts of the spines whitish. Their length is from fifteen to twenty inches.
The food consists mostly of termites but doubtless beetle grubs and other soft-bodied insects are also eaten. They are
SPECIES OF MAMMALS OF THE PACIFIC AREA 15 found in most of eastern Australia, Tasmania (where the hair in the coat of the local race is much more developed), and southern New Guinea.
The Curved-beaked Spiny Anteater (Zaglossus) is a much larger and heavier animal than Tachyglossus. The bill is not only downwardly curved but proportionally much longer, while Fig. 4 — Straight-beaked Spiny Anteater the first and fifth toes are reduced in size. A quite dense hair covering partly hides the spines, much as in the Tasmanian spiny anteater. The color varies from brownish black to much paler, depending upon the amount of white in the spines. The total length is about thirty inches.
This spiny anteater is reported to live in burrows in rocky places and to feed on ants. It is found in New Guinea and Salawati, where it seems mainly confined to mountainous areas. Pouched Mammals or Marsupials.
Order Marsupialia The marsupials are the descendants of an ancient and primitive group of mammals. They are customarily divided into two
16 MAMMALS OF THE PACIFIC WORLD groups, those with only one pair of incisors or front teeth in each side of the lower jaw (Diprotodontia) and those with several lower incisors (Polyprotodontia). Kangaroos, phalangers, honey possum, and wombats are diprotodonts ; bandicoots, "native cats," "pouched mice," and banded anteaters are polyprotodonts. But bandicoots are almost as closely related to diprotodonts.
In all animals of the diprotodont division and in the bandicoots of the polyprotodonts, the second and third toes of the hind foot are very small and united. This strange condition, which may serve as a combing device, gives the appearance of a toe equipped with two claws.
Not all marsupials are characterized by a pouch in the female (the male never has a pouch), but most of them have this nursery bag in which to carry the young. In some types the pouch opens backward. In males the scrotum is situated in front of the penis. All marsupials and monotremes of both sexes have a pair of bones projecting forward from the pelvis in the wall of the abdomen.
Newborn marsupials are tiny, hairless creatures with welldeveloped hands. They find their way hand over hand through the mother's fur into the pouch or to the region of the teats. Each becomes attached by its mouth to a teat and the mother pumps milk into it by contractions of the muscles covering the milk glands, for it is too small to suck.
Apart from a few American marsupials, common opossums and their relatives, these animals are found today only in the New Guinean-Australian region, with representatives on the islands from Celebes and Timor to the Solomons. Ages ago, during the days of dinosaurs, they were also widely distributed in Europe. Many pouched animals in southern New Guinea are so closely related to those on the Australian mainland that they are considered only racially distinct.