MAMMALS FROM WESTERN CIlI>fA. I'M 



slaty. Hands and feet pale brown. Tail uniformly brown above 

 and below. 



Skull shorter and decidedly narrower than in either of the other 

 species ; the brain-case less expanded laterally. 



Dentition : — 



y 1.2.0 pi p 1.2.3.4 ^^ i_^2_^_io 2 = 38 

 -^•0.2.0 ^- 1 '^•1.3.3.4 ^ • 1.2.3—9^" ^'^• 



Upper p'' (the tooth which is absent in Uropsilus sorlcipes 

 and minute in Rhi/nchonaxandersoni) comparatively large, as large 

 as the small anterior pi-emolar in the horizontal area. Below 

 there is no trace of a nainute incisor (ig) behind the large anterior 

 tooth, but, on the other hand, alone in the group, a p^ is present 

 behind the tootli wrongly taken in my previous paper for p^, but 

 really p., ; it is slightly smaller than the corresponding tooth in 

 the upper jaw and is thei'efore the smallest tooth present in the 

 animal. 



Dimensions of the type, measured in the flesh : — 



Head and body 66 mm. ; tail 55 ; hind foot 13-5 ; ear 9. 



Skull: greatest length 20-5; basal length 16-5; zygomatic 

 breadth 10 ; interorbital breadth 5 ; breadth of brain-case 10 ; 

 upper tooth-sei-ies 9'1. 



Hah. and Type as above. 



This delicate little species proves to be of much interest, as its 

 peculiar dentition has caused the discovery of the error in the 

 dental formula of Rhynchonax (under the name of Uropsilus) 

 previously published, and indicates that that animal has in the 

 lower jaw the very unusual premolar formula 1 . 2 . . 4, a formula 

 which in Uropsilus occurs in the upper jaw as well. 



This being the case, it is natural to examine again the 

 dentitions of the nearly allied Urotrickus, Dymecodnn, and 

 Xeurotrichus, and after some consideration I venture to put 

 forward the following as their formulje, modifying tho.se I had 

 previously published : — 



Urotrichiis : — 



y .2.3 ^, 1 p 1- 2.0. 4 ^ 1-2.3_10 ^_„. 



Dymecodon : — 



y 1 . 2 . 3 pi pi. 2 .0. 4 ,. l^J_:J _ W 2- 38 

 ^- 0~r2"73 ^"1 ^-1.2.0.4 ^^'-1.2.3-9^^- ''"• 



XeurotricMis : — 



T^ 1.2.3 pi pO.2 .0.4 ,;r 1.2.3 _ 9 ^_o^ 



^- o"T2T3 ^- i ^- I 72 Ton ^^^-1.2.3-9^ --•^''• 



It will be seen that, arguing from the analogy of the minute 

 teeth of Rhynchonax, wdiich are missing in Uropsilus, I suggest 

 that it is the third lower incisor which is missing in Urolrichus, 



