1894.] 



NATURAL, SCIENCES OF PHILADELPHIA. 



263 



on distal half; pelage moderately coarse, but no spines on rump or 

 elsewhere; ears large; tragus higher than broad ; 

 hind foot very large; skull unlike any known 

 species. P. hailexji is a wide departure from the 

 previously known members of the group. Ex- 

 ternally it resembles P. formosus, but its skull is of 

 a different type, resembling that of paradoxus in 

 size, height, solidity, and general form, but having 

 the large audital and mastoid bullte of formosus. 



Color. — Upper parts drab-brown, abundantly 

 lined with black hairs; under parts white; a pale 

 lateral stripe; tail bicolor, pale dusky above, 

 white beneath. 



Fig. 1. P. biiileyi. Craninl eharacters. —SknW large, heavy, and 

 high, resembling paradoxus in general form and solidity, but with 

 much larger mastoid and audital buUie, the latter nearly meeting 

 anteriorly below basisphenoid ; interparietal squarely pentagonal, 

 broadest anteriorly, ratio of length to breadth about 64. Total 

 length of skull of type specimen, 29-5; mastoid breadth, 15-5; 

 basal length, 24; basilar length of hensel, 20-5; greatest zygomatic 

 breadth (posteriorly), 15-5; length of nasals, 11-5. 



Note. — Specimens have been examined from Magdalena, Sonora, 

 and from New River, Mammoth, and a point 75 miles S. W. of 

 Tucson, in Arizona. 



Perognathus columbianus sp. no v. (Fig. 2). 



Type from Pasco, Plains of Columbia, Washington (on east side 

 of Columbia river, near mouth of Snake river). No. ^''^^l, S , yg. 

 ad., U. S. Nat. Museum, Department of Agriculture Collection. 

 Collected May 9, 1891, by Clark P. Streator. (Original number 

 768.) 



Meaxnrements (taken in flesh). — Type: Total length, 187 mm; 

 tail vertebrre, 96; hind foot, 23. Ear from anterior base, 9 (in dry 

 skinj. Average measurements of 11 specimens from type locality: 

 Total length, 170; tail vertebne, 89-4; hind foot, 22. 



General characters. — Size large; coloration pale; tail long, taper- 

 ing, rather scant haired; mastoid bulhe much swollen; pelage soft. 



Color. — Upper parts smoke gray, darkened oji the back by admix- 



