new Neotropical Mnr'uJce. 365 



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

 strono;lj developed supraorbital edges, narrower posterior nares, 

 and longer pterygoid processes. ]\lolars strictly as in Pero- 

 mi/scus. 



Dimensions of tlie type (a well-nuide skin, male) : — 



Head and body 118 millim. ; tail 142 ; hind foot 25*o (with 

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



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

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

 parietal, length 3'9, breadth 10 ; palate length from heu- 

 selion 11*9; diastema 7'G ; 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 

 mTT 3*7. 



Ilab. Tehuantepec {A. Boucard). 



Type: B M. No. 791.6.3. 



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. J^-Mei-group, 

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



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

 decidedly larger and more darkly coloured than P. leucuruSj 

 while no other described Central-American species attains 

 its size. 



Peromyscus gymnotis, 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 buif, 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 tine 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 



* :Nramm. p. 146 (1880). 



t Bull. Am. Mas. N. H. 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, but they are 

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



Ann. cL- Mag. A'. Hist. Ser. 6. Vol. xiv. 25 



