49o RODENTIA 



distributed throughout South America, extending even to the Straits 

 of Magellan. The Restless Cavy (C. porcellus), which is found 

 throughout Uruguay and Brazil, has been very generally regarded 

 as the ancestral form of the domesticated Guinea-Pig. It is about 

 1 inches long, and weighs a little over a pound ; its fur is long 

 and of a nearly uniform grayish -brown colour. This species is 

 rarely found in dry sandy localities, preferring marshes covered 

 with aquatic plants, among which it lies concealed, feeding in the 

 early morning and after sunset in the evening ; but when the soil 

 is dry it forms burrows. It lives in societies of from six to eighteen 

 individuals, breeding but once a year, with one, or at most only two, 

 young at a birth. The Guinea-Pig (probably a misnomer of Guiana- 

 Pig) is larger than C. porcellus, and is regarded by Dr. Nehring as 

 descended from another species, C. cutleri. It is Avhite in colour, 

 with irregular patches of reddish-brown and black. The Bolivian 

 Cavy (C. boliviensis), found throughout the higher regions of Bolivia, 

 usually at an elevation of 10,000 or 12,000 feet, is exceedingly 

 shy, and lives in burrows, which in some districts are so numerous 

 as to have completely undermined the soil. The Rock -Cavy 

 (C. rupedris), distinguished by its short, blunt nails, is found in rocky 

 situations throughout Brazil, and is much sought after for its flesh. 

 The Southern Cavy (C. cmstralis), common along the coast of Pata- 

 gonia, forms deep burrows, with several outlets, in sandy declivities. 

 Remains of existing species of Cavia are found in the cavern- 

 deposits of Lagoa Santa, Brazil. 



Dolichotis. 1 — Characterised by the great length of the ears and 

 the short tail. The palate is so much contracted in front that the 

 premolars of opposite sides touch by their antero-internal edges. 

 Vertebras : C 7, D 12, L 8, S 3, C 10." 



The Patagonian Cavy (D. patachonica) — the only living repre- 

 sentative of the genus — is rather larger than a Hare, which it 

 somewhat resembles in external appearance. It inhabits the dry 

 sterile districts of Patagonia and La Plata, disappearing wherever 

 the country becomes more humid. This animal burrows in the 

 earth, although in districts where the Viscacha is found it is said 

 to avail itself of the works of the latter. Unlike other cavies, its 

 eyes are protected from the glare of the sun by prominent eyelashes. 

 The body is covered with a long dense fur of a rusty colour. Two 

 young are produced at a birth. Three species of Dolichotis have 

 been described from the Brazilian cave-deposits, one of which is 

 probably not really separable from the existing form. 



Hydrochcerus. 2 — A large aquatic form with all the feet fully 

 webbed ; the skull (Fig. 213, p. 481) large, with enormous par- 

 occipital processes ; and the molars very complex, the third upper 



1 Desmarest, Mammalogie, p. 360 (1822). 

 2 Erxleben, Syst. Beg. Animal, p. 191 (1777) ; ex Brisson. 



