1899.] NATURAL SCIENCES OF PHILADELPHIA. 381 



Legs light smoke gray tinged with bluish gray on inner side of 

 thighs and with broccoli brown on front feet and forearms. Hind 

 feet whitish above. On the front legs the white of the belly ex- 

 tends in a narrow line to wrist ; on the hind legs to feet. 



Skull and Teeth. — The skull of Lepus asellm is about the size 

 of that of L. merriami or the small races of L. texianus. It is con- 

 spicuously smaller than that of Lejms allini or L. texianus texianus. 

 In form it differs from the skull of L. merriami in its broader, 

 deeper rostrum, broader nasals, wider interpterygoid fossa, longer, 

 slightly narrower basioccipital, and slightly larger audital bullae. 



MeasuremenU. — External measurements of type (from fresh 

 specimen by collector) : Total length, 558; tail vertebra?, 62; hind 

 foot, 120; ear from crown, 175. 



Cranial measurements of type: greatest length, 100; basal length, 

 8-1: ; basilar length, 78; henselion^ to posterior edge of bony palate 

 (median), 37; least (lateral) length of bony palate, 7; posterior 

 edge of bony palate to hamular, 21; length of incisive foramen, 

 26; width of incisive foramina, 10.4; zygomatic breadth, 44; inter- 

 orbital breadth (inclusive of supraorbital processes), 30; greatest 

 breadth of braincase, 32.4; breadth of rostrum at base of zygo- 

 mata, 27; greatest (diagonal) length of nasals, 43; greatest 

 breadth across both nasals, 22; least breadth across both nasals, 

 15.4; depth of brain case at anterior end of basioccipital, 30; 

 diastema, 28.4; maxillary molar series (alveoh), 16.8; mandible, 

 74; diastema, 23; mandibular molar series (alveoli), 17. 



Specimens Examined.— 1 have seen only the type of this species. 



General Remarks. — Lepus asellus is readily distinguishable from 

 L. merriami by its somewhat smaller size, relatively as well as ac- 

 tually much longer ears, and gray nape. From the Mexican Lepus 

 callotis, two specimens of which Mr. Jouy collected at Guadala- 

 jara, Jalisco, it is instantly recognizable by its black-tipped ears 

 and gray (not Avhitish) sides. 



Although four names have been based on Mexican jackrabbits, it 

 is easily shoAvn that all refer to animals with white-tipped ears, 

 not in the least like Lepnis asellus. Presumably the first of these 

 is Lepus callotis Wagler {Nat. Syst. der Amphibien mit voran- 

 gehender Classif. der Sdugeth. und Vogel, p. 23, 1830). The 



^ Post-incisive homologue of gnathion. 



