LAGOM VIDA 491 
one having some twelve transverse lamine. Upper incisors grooved. 
Vertebre: C7, D 14, L6, 83, C8. 
The Capybara (H. capybara) is the largest existing Rodent, and the 
only living representative of the genus. It is a bulky and stoutly 
built animal, and attains a length of about 4 feet. The body is 
covered with long and coarse hair, reddish-brown above and brownish- 
yellow beneath. Capybaras are found over the whole of the 
eastern part of South America, and to the westward range into 
Bolivia and Peru. They frequent the borders of rivers and lakes, 
concealing themselves among reeds and other water plants. Remains 
of Hydrocherus are found in the cavern-deposits of Brazil, which are 
probably referable to the existing species ; one extinct species from 
the Pleistocene of Buenos Ayres is estimated to have attained a 
length of 5 feet, while H. magnus of the same deposits was of still 
larger dimensions. The genus is also represented in the Pleistocene 
of South Carolina and the infra-Pampean beds of Parana. 
Extinct Genera—A number of South American fossil Rodents 
have been referred to extinct genera of Caviide. Thus Plexocherus, 
fromthe Tertiary of Argentina, differs from Hydrocherus in having only 
nine lamine in the last upper molar ; Cardiomys, Cardiatheriwm, ete., 
from the infra-Pampeans are also stated to be allied to Hydrocherus, 
while Contracavia, of the same deposits, is related to Cavia, but of 
larger size. Microcavia, again, from the Pleistocene of Argentina, is 
regarded as connecting Cavia with Dolichotis. The Tertiary European 
genera Issiodoromys and Nesocerodon are apparently referable to the 
present family. 
Suborder DUPLICIDENTATA. 
. Two pairs of incisors in the upper jaw (the second very small, 
and placed directly behind the large first pair), the enamel of which 
extends round to their posterior surfaces. At birth there are 
three pairs of these incisors, but the outer one on each side is soon 
lost. Incisive foramina large and usually confiuent ; bony palate 
very narrow from before backwards ; no true alisphenoid canal ; 
fibula ankylosed to the tibia, and articulating with the calcaneum. 
Testes permanently external. This suborder includes the Picas, 
Hares, and Rabbits, all of which are strictly terrestrial. 
Family LAGOMYIDA. 
Complete clavicles, subequal limbs, no external tail, and short 
ears. Skull depressed, frontals contracted and without postorbital 
processes ; p+ or 3; molars rootless, with transverse enamel-folds. 
Palearctic and Nearctic. 
Lagomys.i—Represented by about a dozen species of small 
1 Guvier, Tabl. Elément. de U Hist. Nat. p. 182 (1798). 
