CHAP, xvii.] MAMMALIA. 241 



been found in the Pliocene and Miocene deposits of Europe, and 

 one in the Pliocene of Nebraska in North America. 



The Cavies and Agoutis were placed in distinct families by 

 Mr. Waterhouse, in which he is followed by Professor Carus, but 

 they have been united by Professor Lilljeborg, and without pre- 

 tending to decide which classification is the more correct I follow 

 the latter, because there is a striking external resemblance be- 

 tw^een the two groups, and they have an identical distribution in 

 the Neotropical region, and with one exception are all found east 

 of the Andes. Dasyprocta (9 sp.), the agouti, ranges from Mexico 

 to Paraguay, one species inhabiting the small West Indian islands 

 of St. Vincent, Lucia, and Grenada ; Calogenys (2 sp.), the paca, is 

 found from Guatemala to Paraguay, and a second species (some- 

 what doubtful) in Eastern Peru; Hydrochcerus (1 sp.), the capybara., 

 inhabits the banks of rivers from Guayana to La Plata ; Cavia 

 (9 sp.), the guinea-pigs, Brazil to the Straits of Magellan, and one 

 species west of the Andes at Y^a in Peru ; Kerodon (6 sp.), Brazil 

 and Peru to Magellan ; Dolichotis (1 sp,), the Patagonian cavy. 

 from Mendoza to 48° 30'' south latitude, on sterile plains. 



Extinct Caviidce. — Hydrochcerus, Ccelogenys, Dasyprocta, and 

 Kerodon, have occurred abundantly in the caves of Brazil, and 

 the last-named genus in the Pliocene of La Plata. Hydrochcerus 

 has been found in the Post-Pliocene deposits of South Carolina. 

 Cavia and Dasyprocta are said to have been found in the Mio- 

 cene of Switzerland and France. No well-marked extinct genera 

 of this family have been recorded. 



If the determination of the above-mentioned fossil species of 

 Cavia and Dasyprocta are correct, it would show that this now 



