Page:Encyclopædia Britannica, Ninth Edition, v. 15.djvu/442

Rh 420 with three toes, and Alactaga and Platycercomys with five, the last- named distinguished by the total absence of premolars, comprising many species extending from Siberia to Nubia. Subfamily 3. Pedetinse. Molars rootless; cervical vertebra free; metatarsals separate ; hind feet with four digits. Ethiopian. Pedetes coffer, the Cape Jumping Hare, by far the largest species of the family, extends from Mozambique and Angola to the Cape of Good Hope. See JERBOA. Section III. HYSTRICOMORPHA. Zygomatic arch stout ; malar not supported below by a continua tion of the maxillary zygomatic process ; infra-orbital opening large ; FIG. 97. Skull of Hydrochosrui capybara (reduced). mandible with the angular part arising from the outer side of the bony socket of the lower incisor; clavicles perfect or imperfect; fibula distinct. Family 1. OCTODONTIRE. Terrestrial, rarely fossorial or natatorial Rodents, with perfect clavicles and long incisive foramina extending into the maxillaries. Malar with an inferior angle ; molars with external and internal enamel folds ; mammary teats placed high on the sides of the body. Subfamily 1. Ctenodactylinse. Molars seiui-rooted ; malar as in Dipodidse ; the two inner toes of the hind feet with a horny comb and rigid bristles. Ethiopian. Ctenodactylus gufidi and Pcctinator spekei, both from North Africa, alone represent the subfamily ; the peculiar comb-like inner toes are used in dressing the soft fur. Subfamily 2. Octodontinee. Molars semi-rooted or rootless, -with simple enamel folds ; fur soft. Ethiopian and Neotropical. There are six genera, including several species of Rat-like Rodents. Octodon cumingii, common in Chili and Peru, about the size of a Rat, lires like Rabbits in large communities. Petromys typicus is the only African representative. Subfamily 3. Echiomyinae. Molars semi-rooted or rooted, with deep, curved enamel folds ; fur more or less harsh, of ten mixed with spines. Neotropical and Ethiopian. Aulacodus, with A. swindcrianus, the Ground-Rat of western Africa ; the remaining nine genera are all Neotropical. Of these Myopotamus includes M. coypu, about 2 feet in length, the largest species of the family, common in South America, living in burrows near water, and feeding on aquatic plants. Capromys pilorides, nearly as large, is arboreal in habits, and inhabits Cuba and Hayti, where it is the largest indigenous mammal ; the species of this genus are remarkable for the manner in which the liver is divided into minute lobules. Playiodontia tedium is peculiar to Hayti and Jamaica, and in the latter island (besides Bats and Mice, the latter frobably introduced) appears to be the only indigenous mammal. n Loncheres and Echinomys most of the species have the fur mixed with flattened lanceolate spines. Family 2. HYSTRICID^J. Terrestrial or arboreal Rodents, of stout form, with subequal limbs air! :nore or less spiny integument. Malar without an inferior angle ; the facial part of the skull short and broad ; molars with external and intern&quot;! enamel folds. Subfami 7 1. Spingurin.ee. Molars rooted; clavicles perfect; soles of feet tuberculatcd ; teats four ; tail generally prehensile. Arboreal. Nearctic and Neotropical. There arc three genera, including several species. Of these Erethizon dorsatus, the Urson, is distributed- all over the forest regions of North America ; Synetheres ( = Cercolabes) prehensilis, the well-known prehensile-tailed Porcupine of South America (fig. 98), has ths wliole upper surface of the body protected by long whrte-tipped spines ; Chsetomys subspinosus is clothed with strong wavy bristles ; in the last two genera the feet have four digits only. [RODENTIA. Subfamily 2. Hystricinae. Molars semi-rooted; clavicles imperfect ; soles of feet smooth ; teats six ; tail not prehensile. Terrestrial. Palaearctic, Indian, and Ethiopian. Hystrix cristata, the Common Porcupine of southern Europe and northern Africa, is typical of this genus, which includes several other FIG. 98 Synetheres prehensilis. species from the Indian region. The spines are cylindrical, the tail short and covered with spines and slender stalked open quills. In Atherura fasciculata of the Malay Peninsula the spines are flattened, and the tail is long and scaly, with a tuft of compressed bristles. A closely allied species, A. africana, inhabits western Africa. See PORCUPINE. Family 3. CHINCHILLID.B. Terrestrial Rodents, with elongated hind limbs, bushy tails, very soft fur, and perfect clavicles. The malar is without an inferior angle, and extends forwards to the lacrymal ; the palate is con tracted in front and deeply cmarginate behind ; the incisors are short, and the molars divided by continuous folds into transverse laminte. Neotropical. This small family includes only three species, divided into as many genera. Chinchilla lanigera and Lagidium peruanum are restricted to the alpine zones of the Andes from the northern boundary of Peru to the southern parts of Chili, and Lagostomus trichodactyhis, the Viscacha, to the pampas from the Uruguay river to the Rio Negro. In Chinchilla the fore feet have five and the hind four digits, the tail is long and bushy, and the auditory bullse are enormous, appearing on the top of the skull ; Lagidium has four digits in both fore and hind feet, and Lagostomus three only in the hind feet, while the auditory bullse are much smaller. See CHINCHILLA. Family 4. DASYPROCTID.E. Terrestrial Rodents, with subequal limbs, hoof-like claws, short or obsolete tail, and rudimentary clavicles. Mandibular masseteric ridge obsolete ; palate broad ; incisors long ; molars semi-rooted, with external and internal enamel folds. Neotropical. With two genera: Dasyprocta, including several species of slender- limbed, subungulate Rodents with three hind toes, inhabiting Central and South America, one (D. cristata) extending into the West-Indian Islands ; and Ccelogcnys, with five hind tors, remark able for the extraordinary development of its zygomatic arches, which are enormously expanded vertically, forming great convex bony capsules on the sides of the face, enclosing on each side a large cavity lined with mucous membrane internally, and com municating by a small opening with the mouth ; C. paca is about 2 feet long, and, like the species of Dasyprocta, lives generally in the forests or along the banks of rivers. Family 5. DIXOMYIDJE. Terrestrial Rodents, distinguished from Dasyprodidx by the cleft uppt/ lip and rather long and bushy tail, and by the presence of four digits in the fore and hind feet. The manubrium is broad ; the optic foramina are confluent, the incisors broad and the molars rootless, with-folds dividing them into transverse lobes.