Mr.O. Thomas on a new Species o/'Perognatliiis. 40-5 



Skull unusually broad considering its small size. Nasals 

 very broad behind, surpassing in length the premaxillary 

 processes. Interorbital space very broad. Supraorbital beads 

 widely divergent. Anterior and posterior edges of inter- 

 parietal forming two nearly equal curves. Anterior palatine 

 foramina ending in front of '^^ a distance nearly equal to the 

 length of 1^. Posterior nares widely open, rounded. 



Teeth small and delicate. 



Dimensions of the type (B.M. 93. 3. 6. 25), an old male in 

 skin : — 



Head and body 97 millim. ; tail 127 ; hind foot, without 

 claws (damped) 27, with claws 28 ; ear from notch 18. 



Skull (see below). 



Hab. Mineral San Sebastian, Jalisco, Mexico. Coll. 

 Dr. A. C. Buller, Jan. 25, 1893. 



The type specimen of this species being quite old, with the 

 molar teeth much worn down, its small size will readily 

 distinguish it from all its allies, except the still smaller 

 0. Alfarij Allen, from Costa Kica. 



Measurements of the Skulls of the above Species. 



Oryzornys Couesi. 



, .\. ^ 



Hacienda O.fulgens. O.melanotis. 



Type,$. Cubilguitz,d'. Type,cf. Type,c5'. 



millim. millim. millim. millim. 



Basal length (c.) 26-6 304 .... 25-1 



Upper length* (c.) 30-5 34-8 (31-8 1) 29-5 



Zygomatic breadth 17'8 (c.) 17-8 (c.) 15-2 



Nasals, leacrth Ill 14-1 13-2 120 



Interorbital breadth . . (c.) 5-2 .5-9 4-8 5-1 



Breadth of brain-case . 12-7 13-2 .... 12-8 



Interparietal, length . . 3'5 3'3 .... 3*4 



„ breadth.. 7-9 7'8 .... 10-0 



Palate-length 177 15'5 



Diastema 8-6 9-3 9-1 8-1 



Length of palatine fo- 

 ramina 6-2 7-0 7-2 6-8 



Length of upper molar 



series 4-8 4-8 5-2 4-3 



LXVI. — Description of a new *S/?ec^e5 o/Perognathus/z-owt 

 Colorado. By Oldfield Thomas. 



Among a series of what appear, from Dr. Merriam's able 

 monograph, to be Perognathus fiaviis, Bd., collected by 

 Mr, W. G. Smith in Colorado and acquired by the British 

 Museum, there is a single specimen obviously different from 



* To back of interparietal, excluding supraoccipital. 

 t Interparietal lost ; from back of parietal suture only. 



Ann. <C- Mag. N. Jh'M. Ser, 6. VoL xi. 29 ' 



