"Pocket- Mice ^^ of the Genus Heteromjs. 331 



ear, above head lO'O, from Motcli 15 ; heel to front of last 

 foot-pad 12*5. 



Skull : basal length 29*o ; greatest length 34:'0 ; greatest 

 breadth 16'8; nasals, length l-i'o ; interorbital breadth 8'5 ; 

 inter|)arietal, length 4*0, breadth 6*4 ; diastema 9*o ; palate, 

 length 21 ; length of upper tooth-series 5 '6. 



Hah. La Lacuna, Sierra de Juanacatlan, Jalisco, Mexico, 

 7000 feet. Coll. Dr. A. C. Duller, December 1892. 



A male specimen of //. Aileni from Brownsville, Texas, 

 the typical locality, has a caudal length of 110 and a basal 

 length of 26 millim., while a full-grown skull has a greatest 

 length of 30"3 millim., from which it will be seen that that 

 species is considerably smaller than JI. Bulleri. 



ITeteromys Salvini, sp. n. 



Heteromifs lonyicaudatus, Alii. Biol. Cent.-Am., Manira, p. 167, pi. xvii. 

 lig. 2 (1880) (nee Gray). 



Size about equal to that of H. BuUerij but the feet are 

 decidedly shorter, being as short as in //. Aileni. Fur spiny 

 as usual. General colour blackish, rather darker than in 

 most of the other species, grizzled with yellowish on the back. 

 Lower surface pure wiiite, as usual. Outer sides of forearm 

 with a narrow slaty-grey edging, more conspicuous than in 

 H. Aileni and Bulleri, less than in FT. longicaudatus. Hind 

 foot very short, as short as in H. Aileni-, posterior half of 

 sole covered with short brownish hairs ; pads six, as in the 

 larger naked-soled species, the two posterior pads very close 

 together in the median line of the foot. Tail thinly haired, 

 bicolor, but not so sharply and decidedly as usual, brown 

 above, whitish below. 



Skull in size and shape very like that of H, Bulleri, but 

 the interparietal is much more extended transversely, while 

 only of about the same antero-posterior diameter ; its longi- 

 tudinal percentage is therefore only 44 of its transverse. 



Molars proportionally small and slender. 



Measurements of the type (an adult male in skin) : — 



Head and body (c.) 115 millim. ; tail (imperfect at tip) 

 95 + ?; hind foot 26-5 ; heel to front of last foot-pad 11. 



Skull: basal length 28; greatest length 33-6; greatest 

 breadth 15"2; nasals, length 13"1 ; interorbital breadth 7*6; 

 interparietal, length 4*5, breadth 10*2 ; diastema 8*9; palate, 

 length 19*2; length of upper tooth-series 4*4. 



Uah. Duenas, Guatemala. Coll. 0. Salvin, July 31, 

 1873. 



