new Tueo-tucos from Argentina. 39 



usual. The two rows of cheek-teeth a little nearer together 

 than in tucumanus. 



Dimensions of the type (measured by collector in the 

 flesh) :— 



Head and body 170 mm. ; tail 71 ; hind foot 29. 



Skull : condylo-incisive length 45 - 2 ; condylo-basal length 

 43*6 ; zygomatic breadth 29; breadth across swollen part of 

 muzzle 11*8; nasals, length 13'5, breadth anteriorly 7, pos- 

 teriorly 3*9 ; interorbital breadth 10 ; breadth across brain- 

 case 16*1 ; posterior breadth on lips of meatus 26*3 ; palatilar 

 length 21*6 ; upper tooth-series 8'8 ; diagonal diameter of 

 p 4 3"5, of rri 1 3*3. 



TIab. Tucuman. Type from Tapia, about 20 miles north 

 of Tucuman City. Alt. 600 m. 



Type. Adult male, with basilar suture closed. B.M. no. 

 2. 1. 5. 13. Collected 28th October, 1901, by L. Dmelli. 

 Presented by Oldfield Thomas. One specimen only. 



This species is no doubt most closely allied to its geogra- 

 phical neighbour G. tucumanus, but, as may be seen above, 

 differs both in colour and in quite a number of cranial 

 characters as compared with a set of five good examples of 

 the older-known species. 



Ctenomys pontifex, sp. n. 



A medium-sized species without special markings, the bulla) 

 very narrow. 



Size about as in C. latro. Colour above uniform drab- 

 brown without darker markings ; below paler and more 

 buffy. Tail brown above for its whole breadth, whitish 

 below. 



Skull rather narrow, tbe zygomata not widely expanded. 

 Nasals long, nearly parallel-sided, slightly surpassed behind 

 by the premaxillary processes. Brain-case scarcely ridged. 

 Zygomata with the median ascending process rather farther 

 back than usual, the orbital fossae therefore proportionally 

 large as compared with the temporal fossaa. Mesopterygoid 

 fossa narrow. Bullaa long, low and narrow, in marked con- 

 trast to those of C. ?nendocinus } more like those of the other- 

 wise very different C. f rater. 



Incisors and cheek-teeth normal, pt of scarcely greater 

 diameter than m x . 



Dimensions of the type (measured on skin) : — 



Head and body 183 mm. ; tail 77 ; hind foot 34. 



Skull : approximate condylo-incisive length 44 ; zygomatic 

 breadth 26*5 ; muzzle, breadth anteriorly 9*8, between ante- 

 orbital foramina 8 ; nasals, length 18, breadth anteriorly 7, 



