Page:Encyclopædia Britannica, Ninth Edition, v. 14.djvu/763

 739 separated for a considerable distance at the lower end. Their distal articular surfaces, instead of being pulley-like, with deep ridges and grooves, as in other Artiodactyles, are simple, rounded, and smooth. The proximal phalanges are expanded at their distal ends, and the wide, depressed middle phalanges are embedded in a broad cutaneous pad, forming the sole of the foot, on which the animal rests in walking instead of on the hoofs. The ungual phalanges are very small and nodular, not flattened on their inner or opposed surfaces, and not completely encased in hoofs, but bearing nails on their upper surface only. The cervical region is long and flexuous, and the vertebra? of which it is composed are remarkable for the position of the canal for the transmission of the vertebral artery, which does not perforate the transverse process, but passes obliquely through the anterior part of the pedicle of the arch (a con dition only found in two other genera of mammals. Macrauchcniu and Mynnccophaga}. There are no horns or antlers. Though these animals ruminate, the stomach differs considerably in the details of its construction from that of the Pccora. The interior of the rumen or paunch has no villi on its surface, and there is no distinct psalterium or maniplies. Both first and second compartments are remarkable for the presence of a number of pouches or cells in their walls, with muscular septa, and a sphincter-like arrangement of their orifices, by which they can be shut olf from the rest of the cavity, and into which the fluid portion only of the contents of the stomach is allowed to enter. 1 The placenta is diffuse as in the Suina and Tracjulina, not cotyledonary as in the Pccora. Finally, they differ not only from other ungulates, but from all other mammals, in the fact that the red corpuscles of the blood, instead of being circular in outline, are oval as in the inferior vertebrated classes. The following characters apply especially to the llamas. Dentition of adults: incisors ^, canines, premolars f, molars f ; total 32. In the upper jaw there is a compressed, sharp, pointed lauiariform incisor near the hinder edge of the premaxilla, followed in the male at least by a moderate-sized, pointed, curved true canine in the anterior part of the maxilla. The isolated canine-like premolar which follows in the camels is not present. The teeth of the molar series which are in contact with each other consist of two very small premolars (the first almost rudimentary) and three broad molars, constructed generally like those of Camclus. In the lower jaw, the three incisors are long, spatulate, and procumbent ; the outer ones are the smallest. Next to these is a curved, suberect canine, followed after an interval by an isolated minute and often deciduous simple conical premolar ; then a contiguous series of one premolar and three molars, which differ from those of Camclus in having a small accessory column at the anterior outer edge. The skull generally resembles that of Camclus, the relatively larger brain-cavity and orbits and less developed cranial ridges being due to its smaller size. The nasal bones are shorter and broader, and are joined by the premaxillffi. Vertebra: cervical 7, dorsal 12, lumbar 7, sacral 4, caudal 15 to 20. Ears rather long and pointed. No dorsal hump. Feet narrow, the toes being more separated than in the camels, each having a distinct plantar pad. Tail short. Hairy covering long and woolly. Size smaller and general form lighter than in the camels. At present and within historic times they are entirely confined to the western side and southermost parts of South America, though fossil remains have been found in the caves of Brazil, in the pampas of the Argentine republic, and, ao before mentioned, in Central and North America, In essential structural characters, as well as in general appearance and habits, all the animals of this genus very closely resemble each other, so that the question as to whether they should be considered as belonging to one, two, or more species has been one which has led to a large amount of controversy among naturalists. The question has been much complicated by the circumstance of the great majority of individuals which have come under observa tion being either in a completely or partially domesticated state, and descended from ancestors which from time immemorial have been in like condition, one which always tends to produce a certain amount of variation from the original type. It has, however, lost much of its import- 1 The stomach of the camel inhabiting the Arabian desert is com monly looked upon as a striking example of specialized structure adapted or modified in direct accordance with a highly specialized mode of life ; it is therefore very remarkable to find an organ exactly similar, except in some unessential details, in the llamas of the Peruvian Andes and the guanacos of the Pampas. No hypothesis except that of a common origin will satisfactorily account for this, and, pi-anting that this view is correct, it becomes extremely interesting to find for how long a time two genera may be isolated and yet retain such close similarities in parts which in other groups appear readily subject to adaptive modifications. ance since the doctrine of the distinct origin of species has been generally abandoned. The four forms commonly distinguished by the inhabitants of South America are re cognized by some naturalists as distinct species, and have had specific designations attached to them, though usually with expressions of doubt, and with great difficulties in defining their distinctive characteristics. These are (1) the llama, Auchenia glama (Linn.), or Lama peruana (Tiede- mann) ; (2) the alpaca, A. jxicos (Linn.) ; (3) the guanaco or huanaco, A. laianacus (Molina) ; and (4) the vicugna, A. vicugna (Molina), or A. vicunna, (Cuv.). Ths first and second are only known in the do mestic state, and are variable in size and colour, being often white, black, or piebald. The third and fourth are wild, and of a nearly uniform light- brown colour, passing into white below. They cer tainly differ from each other, the vicugna being FIG. 2. Head of Vicugna (from an animal liv- smaller, more slen- ing in the Gardens of the Zoological Society der in its propor- of London). tions, and having a shorter head than the guanaco. It may, therefore, according to the usual view of species, be considered distinct. It lives in herds on the bleak and elevated parts of the mountain range bordering the region of perpetual snow, amidst rocks and precipices, occurring in various suitable localities throughout Peru, in the southern part of Ecuador, and as far south as the middle of Bolivia. Its manners very much resemble those of the chamois of the European Alps ; and it is as vigilant, wild, and timid. The wool is extremely delicate and soft, and highly valued for the purposes of weaving, but the quantity which each animal produces is not great. The guanaco has an extensive geographical range, from the high lands of the Andean region of Ecuador and Peru to the open plains of Pata gonia, and even the wooded islands of Tierra del Fuego. It constitutes the principal food of the Patagonian Indians, and its skin is invalu able to them, as furnishing the material out of which their long robes are con structed. It is about the size of a European red FIG. 3. Heaa of Guanaco (from an animal living deer and is an ia the Gai &quot;deiis of the Zoological Society of elegant animal, London) - being possessed of a long, slender, gracefully curved neck and fine legs. Dr Cunningham, 2 speaking from observa tion on wild animals, says : Natural History of the Strait of Magellan, 1871.