Cenlronycterls aiid Ctenomys from S. America. 639 



Dimensions of the type : — 



Forearm 45 mm. 



Head and body 52 ; tail 18 ; third finger, metacarpus 46"5, 

 first phalanx 18-5 ; lower leg and hind foot 26. 



Skull : length 15 ; zygomatic breadth 10 ; palato-sinual 

 length 5 ; front of canine to back of m" 6*1 ; breadth 

 between outer edges of ?n^ 6'6. 



Hob. Bogava, Chiriqui^ Panama. Alt. 250 m, 



T(/pe. Adult male. B.M. no. 0.7.11.3. Original 

 number 31. Collected 20th October, 1898, by H. J. 

 Watson. 



INlainly distinguishable from C. maximiliani by its very 

 ditfereut basisphenoid pits, 



Ctenomys salt arms, sp. n. 



Size fairly large, about as in Ct. opimus. Fur rather 

 short (about 13 mm. in length on the back) and dull in 

 tone, having neither the length nor glossiness of that of the 

 neiglibouring species. Colour dull ''raw umber ^' above, 

 browner along the median dorsal area, paler on sides. 

 Under surface dull buflfy whitish. Area round snout 

 whitish, succeeded by an inconspicuous darker collar. Feet 

 dull white. Tail more markedly bicolor than usual, blackish 

 above, dull white below. 



Skull very narrow, the zygomatic spread less than the 

 distance from the front of the incisors to the back of the 

 tooth-row, markedly greater in other species. Frontal 

 region also very narrow, the interorbital breadth less than 

 the length of the molar series. Postorbitdl processes 

 practically absent. 



Dimensions of the type (measured in skin) : — 



Head and body (stretched) 200 mm. ; tail 90 ; hind 

 foot 33. Skull : front of nasals to back of frontals 34-8 ; 

 front of incisors to back of m' 29-5 ; zygomatic breadth 28-5 ; 

 nasals 20 X 7*7 ; interorbital breadth 92 ; palatilar length 

 23-8 ; diastema 15 ; upper tooth-series, crowns lO'S, 

 alveoli 1 1 . 



Hab. Salta, N. Argentina. 



Type. Adult female. B.M. no, 99.2.22.26. Original 

 number 8904. Presented bv the La Plata Museum through 

 Dr. F. P. Moreno. 



The only species occurring near this are the far paler 

 Ct. opimus (of which a special subspecies, 67. o. liiteolus, is a 

 native of Jujuy) and the dark brown C7/. tucumunus of 



