NO. 2 NEW MAMMALS FROM EASTERN PANAMA — GOLDMAN II 



and suggest the condition usual in South American -i £ the 



genus. In the adult pelage a few inconspicuous pure white h 

 are irregularly intermingled with the bristles on the back. 



Specimens examined. — Twenty-three, all from 4.500 to about 

 5.000 feet altitude on the upper slopes of the mountains in the 

 vicinity of the type locality. 



HYDROCHOIRUS ISTHMIUS, sp. nov. 



Type from Marraganti, near the head of tide-water on the Rio 

 Tuyra, eastern Panama. No. 179703, male adult. U. S. National 

 Museum (Biological Survey Collection), collected by E. A. Gold- 

 man, April 4, 1912. Original number 21591. 



General characters.- — Similar to Hydrochcerus hydrochecris in 

 color, but size decidedly smaller: skull differing in important details, 

 ■ ally the peculiar, short, thickened condition of pterygoids. 



Color. — Upper and under parts in general varying from very dark 

 rusty reddish to dull pale clay color, usually somewhat darker above 

 than below, becoming more or less blackish in some specimens on 

 middle of face, cheeks, lower part of rum]), and outer sides of hind 

 legs: orbital rings, sides of muzzle and spots near base of ears paler, 

 more buffy ; ears and feet brownish, thinly haired. Young (about 

 one-fourth grown 1 : Upper parts more tawny ochraceous than in 

 adults. 



.V /:////.- --Smaller than that of hydro cheer is; nasals with inner bor- 

 der more extended forward over anterior nares, approaching median 

 projection of premaxilke; maxillary portion r wall of antorbi- 



tal vacuity broader; maxillo-premaxillary suture passing further for- 

 ward along upper surface of rostrum, and turning thence more 

 abruptly downward: incisive foramina relatively narrower: pre- 

 maxilke with posteriorly extended portions reaching to near poste- 

 rior plane of incisive foramina (ending well in front of this plane in 

 hydro cheer is) ; pterygoid processes shorter, thicker, more rounded, 

 less produced posteriorly; dentition about as in hydrochceris, but 

 relatively lighter. 



Measurements. — Type: Total length, 1,025 nim., hind foot, 200. 

 Average of two adult females: 998 (972-1,025); [97 (195-200). 

 Skull (type): Greatest length. 200; zygomatic breadth. 116. 5; 

 interorbital breadth, 52.^,: length of nasals .''.long inner side, 79.8; 

 width of nasals posteriorly, 47.7: palatal length, [22; length of 

 palatal bridge. 70.8; alveolar length of maxillary tooth row, 04.2. 



Remarks. — The capybara is among the more interesting mammals 

 whose known ranges are found to extend into Panama. The 



