new Neotropical Muridse. 365 



of P. azfecus, De Sauss. It is, however, larger, with more 

 strongly developed supraorbital edges, narrower posterior nares, 

 and longer pterygoid processes. Molars strictly as in Pero- 

 myscus. 



Dimensions of the type (a well-made skin, male) : — 



Head and body 118 millim. ; tail 142 ; hind foot 25"5 (with 

 claws 2(r5) ; ear from notch 17*5. 



Skull: greatest length 30'3, greatest breadth 15; nasals, 

 length 11*2, breadth 3*4; interorbital breadth 5*1 ; inter- 

 parietal, length 3*9, breadth 10 ; palate length from hen- 

 selion 11*9; diastema 7*6 ; palatal foramina 5'8 x 2 - 4 ; length 

 of upper molar series 4*5. Lower jaw : condyle to incisor- 

 tip 18 2; coronoid to angle 7'4 ; height of ramus below 

 sn3-7. 



Hob. Tehuantepec (A. BoucaroT). 



Type: B M. No. 79.1.6.3. 



This species is founded on the Tehuantepec specimen re- 

 ferred by Alston in the ' Biologia ' * to "Hesperomys cali- 

 jornicus." It differs from that species by its smaller size, 

 smaller ears, much paler colouring, and more thinly haired 

 tail. It is perhaps most nearly related to the P. ZW/ea-group, 

 of which it may be said to be a large small-eared member. 



Mr. Allen's Peromyscus nudipes f from Costa Rica is 

 decidedly larger and more darkly coloured than P. leucurus, 

 while no other described Central-American species attains 

 its size. 



Peromyscus gym?iotis, sp. n. 



Size medium ; ears long, tail short. General colour, so 

 far as can be made out in a spirit-specimen, very dark, almost 

 bistre-brown. Under surface dirty buff, the slate-coloured 

 bases of the hairs showing through. Ears long, laid forward 

 in a spirit-specimen they reach 3 or 4 millim. in front of the 

 anterior canthus of the eye ; perfectly naked, no hairs being 

 discernible upon them (except at their bases posteriorly) even 

 with a lens J ; their substance plumbeous in colour. Palate- 

 ridges 3 — 5. Hands and feet thinly covered with fine silvery- 

 white hairs ; fifth hind toe reaching to the base of the second 

 phalanx of the fourth ; soles practically naked along median 

 line, a few scattered white hairs being only found on this 



* Mamrn. p. 146 (1880). 



t Bull. Am. Mus. N. II. iii. p. 213 (1891). 



X A second examination with a more powerful lens shows that there 

 are a few widely scattered minute whitish hairs on the ears, hut they are 

 so few and so small as practically not to affect the statement in the text. 



Ann. & Mag. JS. Hist. Ser. 6. Vol. xiv. 25 



