132 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



signs of regular use and where it was completely hidden until dis- 

 lodged by my close approach. A burrow, evidently that of the paca, 

 entered the ground at the base of a neighboring tree. 



Specimens examined : Divala, i * (type) ; Gatun, 8 ; Rio Indio 

 (near Gatun), 7. 



Family CAVIIDAE. Cavies and Capybaras 

 A single representative of this family, the capybara, until the 

 present survey known only from South America, is among the more 

 interesting mammals whose ranges are now found to extend into 

 Panama. 



Genus HYDROCHOERUS Brisson. Capybaras 

 As the largest existing rodents the capybaras, genus Hydrochocnis, 

 are at once distinguished from the other members of the order. 

 They are robust animals about three feet in length, the body thinly 

 clothed with coarse hair. The webbed feet show adaptation for an 

 aquatic life. 



HYDROCHOERUS ISTHMIUS Goldman 



Isthmian Capybara; Poncho 



[Plate 28, figs. I, la] 



Hydrochoerus isthmius Goldman, Smiths. Misc. Coll., Vol. 60, No. 2, 

 pp. 11-12, September 20, 1912. Type from Marraganti, near the head of 

 tide-water on the Rio Tuyra, eastern Panama. 



The capybara of Panama is decidedly smaller than Hydrochoerus 

 hydrochocris of northeastern South America and it differs in numer- 

 ous important cranial details, especially the peculiar, short, thickened 

 condition of the pterygoids. 



On the Pacific coast of Panama it is apparently restricted to a 

 limited area near the head of tidewater in the delta region of the 

 Tuyra and Chucunaque rivers. A skull from " Atrato " collected by 

 A. Schott, who accompanied Michler's expedition through the Darien 

 region, seems referable to the same species which may therefore 

 prove to have a wide range in the Atrato river valley. Anthony 

 (1916, p. 371) records the species from El Real de Santa Maria. 



At Marraganti many tracks were seen at low tide in early morning 

 where the capybaras had crossed exposed mud banks between the 

 water in the river and low-lying areas overgrown with tall swamp 

 grass and other aquatic vegetation. Capybaras were found during 

 the day occupying shallow beds hollowed in the ground, or wallow- 

 ing in muddy pools, in secluded parts of the swamp. Sometimes they 



' Collection Mus. Comp. Zool. 



