142 Mr. O. Thomas on 



Under surface drab ; axillary and inguinal white patches 

 present or absent. Cliin and a darker area across chest 

 brown, separated from each otlier by an inconspicuous drabby 

 collar. Hands and feet drabby whitish. Tail drabby or 

 brown above, rather lighter below. 



Skull smaller than that of G. opimus, larger than in frater 

 and tucumanus. Nasals fairly broad, evenly narrowing back- 

 wards. Postorbital processes well marked. Interparietal 

 distinct in all four specimens, its front edge evenly convex, 

 its hinder edge more or less directly transverse. Bull*, in 

 shape and proportionate size, about as in C. tucumanus, 

 smaller than in opimus, not so peculiarly narrowed as in 

 frater. Ectocondylar processes of lower jaw scarcely 

 developed. 



[Besides these normal characters of the skull it should be 

 mentioned that there are, on both sides in three specimens 

 and on one in the fourth, small triangular supplementary 

 bones at the front edge of the parietals, bordering the frontals. 

 Presumably these extra bones are abnormal, but their nearly 

 constant presence in the four specimens of C. budini renders 

 them worthy of mention.] 



Dimensions of the type (measured in the flesh) : — 



Head and body 210 mm. ; tail 68 ; hind foot 33. 



Skull : greatest length 48'3 ; condylo-incisive length 49 ; 

 condylo-basal length 47*2; zygomatic breadth 31; nasals 

 17 X 8'5 ; iiiterorbital breadth ll'S ; breadth across brain- 

 case behind zygomata 18'8 ; tympanic breadth 30 ; palatilar 

 length 22'2 ; upper tooth-series (alveoli) 10"2. 



Hab. as above. 



Type. Adult male. B.M. no. 12. 12. 12. 37. Original 

 nuniber 48. Collected 1st April, 1912. 



This Tuco-tuco is most nearly allied to G. frater and 

 tucumanus, but is readily distinguishable from the former by 

 its more evenly swollen bullae, from the latter by its greater 

 size, and from both by its distinct interparietals. All four 

 skulls of G. budini have this bone large and clearly marked, 

 while it is absent in both skulls of G. /rater and in four out 

 of five skulls of G. tucumanus, the fifth having a very small 

 one present. 



Whether the peculiar extra fronto-parietal bones will 

 prove to be a normal character of the species remains to be 

 seen, but they may be simply a family character of the 

 individuals sent home. 



I have had pleasure in naming this distinct species after 

 Sr. E. Budin, to wdiose labours this most excellent collection 

 is due. 



