June, 1903. A List of Mammals — Elliot. 219 



being, as I believe, the adult pelage. Dr. Allen states (1. c.) that " the 

 young show a marked suffusion of fulvous," but this is not per- 

 ceptible in this series, and I think it possible that two forms may have 

 been confounded, those from the foothills and coast and those from 

 the mountains, for two species are apparently represented in the 

 series of 45 specimens from this region. All the examples of 

 T. martirensis have a grayish tinge, even among those with an och- 

 raceous buff pelage, and none of them exhibit the dark hues of T. 

 fulvus. The skulls vary considerably and it does not seem possible 

 to give any cranial character by which the species can be certainly 

 recognized, but, as I have already mentioned, the nasals are gen- 

 erally longer, and the average size of the individuals is larger. It is 

 a pale colored form in youth, and dark gray in old age. At all 

 events that is the impression these examples give, and no fulvous 

 series is perceptible. 



Thomomys* aphrastus, sp. nov. 



16 Specimens: Type locality. San Tomas, Lower California, 

 Mexico. 



Genl. Char. About the size of T. fulvus, but darker and grayer. 

 Nasals short, broad at anterior end, pterygoids almost touching the 

 bullae. 



Color. Upper parts mixed broccoli brown and ochraceous, the slate 

 of base of hairs occasionally showing and giving a grayish tint to 

 the pelage; sides bright ochraceous buff; spot behind ear, nose and 

 openings of pouches black; under parts ochraceous buff, plumbeous 

 or slate of under fur showing; hands and feet grayish white; tail 

 ochraceous buff above, yellowish beneath. (March.) 



Another specimen from San Quentin, July, is lavender gray, 

 darkest on dorsal region, with top of head ochraceous buff and black, 

 and sides of head pinkish buff; sides of body buffy gray and under 

 parts buff. This individual is beginning to change from gray to the 

 darker pelage of winter. 



Measurements. Total length, 222, tail vertebrae, 69; hind foot 

 29; ear, 7.5. Skull: occipito-nasal length, 38; Hensel, 35; interorbital 

 constriction, 6; zygomatic width, 25; length of nasals, 12.5; anterior 

 width of nasals, 4.5; palatal length, 23; length of upper molar series, 

 7.5; length of mandible, 22; length of lower molar series 7; height at 

 coronoid process, 15. 



This is a rather smaller species than T. martirensis, has much 

 shorter nasals, and seems to be restricted to the lowlands and foot- 



*(p(ppa<jToq — perplexing. 



