PORCUPINES. CAVIES. 635 



Tribe 3. Hystrieomorpha. 



With stout zygomatic arch, clavicles perfect or imperfect, fibula distinct, 

 infraorbital foramen large, p \. 



Fain. 12. Pedetitae. With rooted molars, cervical vertebrae free, 

 hind limbs elongate, metatarsals free, pes tetradactyle, Ethiopian. Pe- 

 detes 111., 1 sp. ; P. kaffer, the Cape jumping-hare. 



Fam. 13. Octodontidae. Clavicles complete, grinders with external 

 and internal enamel folds, anterior palatal foramina long extending into 

 maxillae, maniis and pes usually with 5 digits, teats high up on the flanks, 

 tail with short hairs or scales, usually terrestrial, occasionally fossorial 

 or aquatic, all Neotropical unless otherwise mentioned, 21 genera. Lou- 

 che) es 111., porcupine-rats, with small spines in the fur, 18 sp. Thrynomys 

 Fitz. (Aulacodus), ground rat of S. Afr., 4 sp., Eth. Myocastor Kerr 

 (Myopotamus), 1 sp. ; M. coypu, the coypu, a large S. American water- 

 rat, to 2 feet. Ctenodactylus, 1 sp., Eth. Massoutiera, 1 sp. Eth., 1 sp. 

 Palaearct. Pectinc'tor, 1 sp., Eth. Petromys, 1 sp., Eth. Ctenomys, 

 9 sp. Aconaemys (Schizodon), 1 sp. Spalacopus, 1 sp. O.'todon, 4 sp. 

 Abrocoma, 2 sp. Dactylomys, 1 sp. Thrinacodus, 1 sp. Kannabateomys, 

 1 sp. Thrichomys, 4 sp. Cercomys, 1 sp. Carterodon, 1 sp. Mesomys 

 4 sp. Echinomys, 13 sp. Capromys, 5 sp. Plagiodontia, 1 sp. 



Fam. 14. Hystricidae. Porcupines. Fur more or less modified 

 into spines and hollow quills, tail not prehensile, soles of feet smooth, 

 grinding teeth with external and internal folds ; skull bones often inflated 

 by air-sinuses, clavicle incomplete, limbs sub-equal. Hystrix L., Ethiop. 

 3 sp., Orient. 7 sp., Palaearct. 2 sp ; H. cristata, the common porcupine, 

 S. Eur., N. and W. Afr. Atherura G. Cuv., Ethiop. 3 sp , Oriental 1 sp 

 Trichys Gunth., Orient., 1 sp. 



Fam. 15. Erethizontidae. Hair as in last, clavicles complete, soles 

 tuberculated, tail usually prehensile, Neotropical except Erethizon F. Cuv., 

 Nearctic, 2 sp ; Coendu Lac. (Cercolabes and Synetheres, Sphingurus), tree 

 porcupines, arboreal, Neotrop. 9 sp. Chaetomys Gray, Neotrop., 1 sp. 



Fam. 16. Chinchillidae. Terrestrial, with long hind limbs, bushy 

 tails, soft fur, and complete clavicles, grinders lophodont, all Neotropical. 

 Chinchilla Benn., 1 sp., squirrel-like, fur grey, valuable; Andes. Lagidium 

 Mey., 3 sp. Lagostomus Brooks, 1 sp. L. trichodactylus, viscacha, live in 

 burrows. 



Fam. 17. Dasyproctidas. With long incisors, sub-equal limbs, hoofs 

 like claws, short tail, Neotropical. Dasyprozta 111., agoutis, pes with 

 3 digits, C. and S. Amer. and W. Ind. Islands, 12 sp. ; Coelogenys F. Cuv., 

 paca, pes with 5 digits, jugal arch very broad, enclosing on each side a 

 cavity communicating with the mouth, body attains a length of 2 feet. 



Fam. 18. Dinomyidae. Cleft upper lip, long bushy tail, limbs tetra- 

 dactyle, 1 genus and sp. and only 1 specimen found, Peru. Dinomys Pet. 



Fam. 19. Caviidae. Terrestrial or aquatic with short incisors, lopho- 

 dont grinders, milk teeth shed in foetal life, paroccipital processes long and 

 curved, clavicles imperfect, tail short, manus with 4, pes with 3 digits, 

 Neotropical. Cavia Pall., cavies, 11 sp. ; C. porcellus, guinea pig. Doli- 

 chotis Desm., 2 sp., Patagonian cavy. Hydrochoerus Briss., 1 sp., H. 

 capybara, capybara, aquatic, the largest rodent, length 4 to 5 feet, without 

 tail, manus tetra-, pes tri-dactyle, digits webbed, hoof-like nails, last u. 

 molar very large with 14 laminae. 



