Page:Encyclopædia Britannica, Ninth Edition, v. 15.djvu/462

Rh 438 MAMMALIA [CARNIVORA. quite intermediate) between that of the .ZEluroid and Arctoid forms. In .the number and arrangement of the teeth they more nearly approach the primitive heterodont type than any other existing Carnivora. A caecum is always present, sometimes short and simple, but when long it is folded upon itself in a characteristic manner. The Dogs form a very compact group, composed of numerous species which closely resemble each other in essential characters, though differing considerably externally. The most marked differences are a slight variation in the number of the true molar teeth, which exceed the usual number in the Cape Long-eared Fox (Otocyon), and fall short of it in some other less aberrant forms to which the names of Idicyon and Cyan have been given, and a diminution in the number of toes in the Cape Hunting Dog (Lycaon), which has 4-4, instead of 5-4 as in the remainder of the family. After taking these away, there remain a great number of animals called Dogs, Wolves, Jackals, and Foxes, varying from one another only in the characters of the tail, ears, fur, form of the pupil, and some trifling peculiarities of skull and teeth, upon which some authors have divided them into many genera. These divisions are, however, extremely difficult, if not impossible, to define, on account of the numerous gradual transitions from one form to the other. Canis. Pending further investigation, it will perhaps be safest to retain all the species, with the exceptions of Otocyon and Lycaon mentioned above, in the old genus Canis, the most prominent characters of which are the following. Teeth, usually i f, c , p , m = ir ! total 42. The absence of the last upper molar (m 3), alone distinguishes this from the generalized dentition of heterodonts (see p. 353), and this tooth is occasionally present in one species (0. cancrivorus). In certain Asiatic species ( C. primeevus and its allies), which on this account have been separated to form the genus Cyan of Hodgson, the last lower molar (m 3) appears to be con stantly absent, and in C. venations (genus Idicyon, Lund) not only this but also in 2 is usually not developed. The milk dentition is di f, dc, dm f = f ; total 28, the first permanent premolar having no predecessor. The teeth of both permanent and milk or temporary series are figured at p. 353 (fig. 3). The upper sec- torial p 4 consists of a stout blade, of which the anterior cusp is almost obsolete, the middle cusp large, conical, and pointed back wards, and the posterior ciisp in the form of a compressed ridge ; the inner lobe is very small, and placed quite at the fore part of the tooth. The first molar is more than half the antero-posterior length of the sectorial, and considerably wider than it is long ; its crown consists of two prominent conical cusps, of which the anterior is the larger, and a low broad inward prolongation, supporting two more or less distinct cusps and a raised inner border. The second molar resembles the first in general form, but is considerably smaller. The lower sectorial m 1 is a very large tooth, with a strong compressed bilobed blade, the hinder lobe being considerably the larger and more pointed, a small but distinct inner tubercle placed at the hinder margin of the posterior lobe of the blade, and a broad, low, tuberculated heel, occupying about one-third of the whole length of the tooth. The second molar is less than half the length of the first, with a pair of cusps placed side by side anteriorly, and a less distinct posterior pair. The third is an extremely small and simple tooth with a subcircular tuberculated crown and single root. The cranium is more or less elongated, the facial portion taper ing forwards and compressed. The jaws elongated. The zygomata moderately strong. The post-orbital processes of the frontal short, leaving the orbit widely open posteriorly. Vertebra : C 7, D 13, L 7, S 3, C 17-22. Clavicles present, but very rudimentary. Limbs of moderate proportions, digitigrade. Feet shoVt ; five toes 011 the fore foot, the pollex much shorter than the others, and not reaching to the ground. Four toes on the hind foot, the hallux being repre sented by a rudiment of the metatarsal. 1 All the toes are provided with exserted non-retractile slightly curved and blunt claws, which, being exposed, become worn at the tips. Tail moderate, or rather long, generally somewhat bushy. The pupil of the eye, when con tracted, is in some species round, in others elliptical and vertical. This extensive genus may be considered as truly cosmopolitan. One or more species are found throughout the American continent from Greenland to Patagonia and the Falkland Isles ; and similarly, in the Old World, Europe, Africa, and Asia, with most of the large islands adjacent, and even Australia, have their wild Dogs, though in the last case they probably belong to a feral race, introduced originally by man. They are generally sociable animals, hunting their prey in packs. Many species burrow in the ground ; none habitually climb trees. Though mostly carnivorous, feeding chiefly on animals they have chased and killed themselves, many, especially among the smaller species, eat garbage, carrion, insects, and also fruit, berries, and other vegetable substances. The species 1 In Domestic Bogs a hallux is frequently developed, though often in a rudi mentary condition, the phalanges and claw heing suspended loosely in the skin, wi .hout direct connexion with the other bones of the foot; it is called by dog- fanciers the &quot;dew cl iw.&quot; are very numerous, and, as in most other large genera, very ill- defined, few zoologists agreeing as to which of the many slightly different modifications may be considered as local varieties and which true species. Perhaps the best cranial character by which the different members of the genus can be distinguished is that pointed out by Burmeister, viz., that in the animals generally called Dogs, Wolves, and Jackals the post-orbital process of the frontal bone is regularly smooth and convex above, with its extremity bent downwards, whereas in Foxes the process is hollowed above, with its outer margin (particularly of the anterior border) somewhat raised. This modification coincides in the main with that upon which Professor Huxley has recently 2 based his division of the group into two parallel series, the Thooids or Lupine forms and Alopecoids or Vulpine forms, which he characterizes ly the presence of frontal air-sinuses in the former, which not only affects the exter nal form but to a still greater degree the shape of the anterior part of the cranial cavity, and the absence of such sinuses in the latter. The pupil of the eye when contracted is round in most members of the first group, and vertically elliptical in the others, but more observations are required before this character can be absolutely relied upon. The form and length of the tail is often used for the purposes of classification, but its characters do not coincide with those of the cranium, as many of the South American Canidse have the long bushy tails of Foxes and the skulls of Wolves. Taking into account various combinations of these and other minor characters, the species may be arranged in the following groups, which some authors have considered as of generic importance. A. Thooid or Lupine Series. (1) Canis proper contains the largest members of the genus, the true Wolves of the northern parts of both Old and New Worlds (0. lupus, &c.), the Jackals of southern Asia and Africa (C. aureus, mcsomelas, &c. ), and the various breeds of the domestic E&amp;gt;og (0. familiar is), the origin of which is still involved in obscurity. Some naturalists believe it to be a distinct species, descended from one that no longer exists in a wild state; others have sought to find its progenitors in some one of the wild or feral races, either of true Dogs, Wolves, or Jackals ; while others again believe that it is derived from the mingling of two or more wild species or races. It is probably the earliest animal domesticated by man, and few if any other species have undergone such an extraordinary amount of variation in size, form, and proportion of limbs, ears, and tail, variations which have been perpetuated and increased by careful selective breeding. See DOG. The Dingo or Australian Dog is met with wild, and also as the domestic companion of the aboriginal people. Dogs Avere also in the possession of the natives of New Zealand and other islands of the Pacific, where no placental mammals exist naturally, on their discovery by Europeans in the last century. (2) Cyon, wild Dogs of the south-east of Asia, distinguished by slight modifications as C. prim&vus, C. dukh- enensis, and C. sumatrensis, differ from the above in wanting the small last* lower tubercular molar. (3) Lycalopex is a group formed of certain South-American Canidse, distinguished from Canis proper by their longer tails and Fox-like aspect:- C. cancrivorus, C. brasili- cnsis, C. melampus, C. vetulus, C.fulvicaudus, C. azarae, C. mcgellani- cus, C. griseus. The last three have been further separated (under the name of Pscudalopex) on account of slight differences in the relative size of the molar teeth, and of their pupil being elliptical when con tracted. (4) Nyctcrcutes (one species, C. procyonidcs, from Japan and north-east Asia) has no claims to generic distinction but such as are founded upon its long loose fur, short ears, and short bushy tail, which give it some superficial resemblance to a Raccoon. (5) Icticyon, with one small species, C. vcnaticus, the Bush Dog, from Guiana and Brazil, with close hair, and short legs and tail, has more reason to be regarded as a distinct form, as it is distinguished from all other Dogs by the reduction of its molar teeth to ^, and their comparatively small size. In consequence of this, and its general external characters, it was formerly placed among the Mustclidx, but its Canine affinities have now been thoroughly established. B, Alopccoid or Vulpine Series. (6) Vulpcs, true Foxes. The species or varieties are numerous and widely spread over North America, Eurasia, and Africa : C. vulpes, the common Fox of Europe ; C. niloticus, adustus, and varicgatus, Africa; C. flavescens, montanus, bengalensis, japonicus, corsse, Asia; C.fulvus, macrourus, velox, North America. The tail of the above is clothed with soft fur and long hair, uniformly mixed ; from them Baird distinguishes, under the name of Urocyon, other species which have a concealed erect mane of stiff hairs along the upper line of the tail. These have also a shorter muzzle and a wide space between the temporal crests; they are C. virginianus and C. littor- alis, both from North America. The Arctic Fox (C. lagopus, genus Leucocyon, Gray) has the tail very full and bushy and the soles of the feet densely furred below. Its colour changes according to serson from bluish-grey to pure white. (7) Fennecus. Certain small elegant African Foxes (C. ccrdo, famclicus, and chama), with very 2 Proc. Zoot. Sot. Lond., 1880, p. 238-