MUllID^E— SIGMODONTES— HESPEROMYS TOEEIDUS. 



109 



mens before us, and we do not doubt its constancy. It is well shown in Audu- 

 bon's left-hand figure. 



One young specimen (No. 3092) from the Medicine Bow Mountains, in 

 the gray pelage, is remarkably pale-colored above, the tail nearly white, &c 

 This corresponds exactly with the pale Hesperomys var. sonoriensis and the 

 pale Arvicola of the Pedomys section, from the same region. 



The only skull before us (No. VhV") offers the following measurements: — 

 Length, 1.07; interorbital width, 0.20 (the zygomata are destroyed); width 

 across cranium, 0.48 ; lower jaw, from tips of incisors to condyle, 0.72 ; length 

 of upper molar series, 0.19. 



Table XXX. — Measurements of nine specimens of Hesperomys (Onychomys) leucogaster. 



Date. 



Locality. 



Collector. 



Nose to- 



Remarks. 



H . i> 



ftm 



l 2549 

 7492 

 4007 

 3092 

 3091 

 3378 

 3703 

 3704 



,1855 



Near Missouri River . 

 do 



July 23, 1857 

 Sept. 10, 1857 



Ruimiugwater 



Fort Riley, Kans 



Medicine Bow Mountains . . 

 Republican River, Kans. Ter 



Neosho Falls, Kans. Ter 



do 



do 



F. V. Hayden . 



...do 



...do 



0.60 

 0.60 



1.07 

 1.00 



1.25 

 1.28 



H. Brandt . . 

 W. S.Wood. 



...do 



B. F. Goss... 



...do 



..do 



0.61 

 0.50 

 0.58 



1. 00 1. 15 

 1. 00 1. 15 



4.00 

 4.00 

 4.35 

 3.50 

 3.50 

 4.50 

 4.50 

 4.25 

 4.40 



1.40 

 1. 80 0. 52 

 1. 05 0. 50 

 1. 00 0. 40 

 1.30 0.40 



0.88 

 O.K. 

 0.S8 

 0.70 

 J. 76 



t. GO 0.44 0.87 

 1. 30 0. 42 83 

 1.50 0.50 0.82 

 1.40 0.53 0.85 



* Other measurements of 2549, given by B;md, are:— Fore arm, 0.82; longest finger and claw, 34; its claw alone, 

 0.20; femur, 0.85; tibia, 1.05; longest toe and claw, 0.30; its claw alone, 0.14. 



HESPEROMYS (ONYCHOMYS) TORRIDUS, Coues. 



Arizona Mole-Mouse. 

 Hesperomys (Onychomys) torridus, Cooes, Proc. Acatl. Nat. Sci. Phila. 1374, 183. 



Diagnosis. — O. imaginem O. leucogastris referens, sed caudd longiore, au- 

 riculis praclpue major/bus, plant/'* minus pilosis, unguibus vianiis debilioribus, 

 et coloribus magis Jlavescentibus, primo visu differt ; murino-fulvus ; rostro toto, 

 pedibus, par tibusque omnibus inferioribus jluvo-albis ; caudd lined fused angus- 

 tatd nee ad apkem porrectd supra notatd. Long. 3f, caudal 2, manus f, pedis 

 I, auricula) fere f. 



Habitat. — Arizona. 



(No. D886, 9.) — On comparing this animal with typical leucogaster from 

 Kansas and Nebraska, the differences in general form are obvious. Truly 

 Onychomys, with Jhe unmistakable aspect of that section, yet the members are 



