MURIDA—SIGMODONTES—HESPEROMYS TORRIDUS. 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 Mountaius, in 
the gray pelage, is remarkably pale-colored above, the tail nearly white, &« 
This corresponds exactly with the pale Hesperomys var. sonoriensixs and the 
pale Arvicola of the Pedomys section, from the same region. 
The only skull before us (No. 4s30') 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. 
Nose to— | 
A te Be ee EY en = oe) + 
3 Date. Locality. Collector. = s s Remarks. 
| i ES |leesall cee lksdes| isi] eae sto less 
| 
£34 |---.| ———, 1855] Near Missouri River ......- F. V. Hayden .....|....|.-. |.---|4.00]1. 40 ....|0.88|....) Dry. 
eat ON oe 3| ocogsacesemas beccce OO)ssessctases cet esc Se: 5/4. 00/1. 80 0. 52/0. 850. 46) Alcoholic. 
7492 |.... .| Runningwater .. .- }4. 25/1. 65 0. 50)0, 88/0. £0)... .do. 
4607 | 9 Fort Riley, Kans --- eee -./3. 50} 1. 00 0. 40/0. 70/0. 40) Not grown. 
3092 | # | July 23,1857 | Medicine Bow Mountains --. ../3. 50/1, 30 0. 40/0. 76/0. 52)... .do. 
3091 | of | Sept. 10, 1857 | Republican River, Kans. Ter |.... 4. 50/1. 60 0. 44/0. 87/0. 52) Stretched. 
GSI |e pe eons Neosho Falls, Kans. Ter . - -- 4. 50) 1. 30 0.42 @ 83)0. 48) Dry. 
3703 | & 4, 25) 1. 50 0. 50,0. #2)0. 53)... .do. \ 
3704 | + /4. 40)1. 40 0. 53/0. 85,0. 52). ...do. 
: | | 
* Other measurements of 2549, given by Baird, are:—Fore arm, 0.82; longest finger and claw, 0.34; 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, Cours, Proc. Acad. Nat. Sci. Phila. 1874, 183. 
Draanosis.—O. imaginem O. leucogastris referens, sed cauda longiore, au- 
riculis precipue majoribus, plantis minis pilosis, unguibus manus debilioribus, 
et coloribus magis flavescentibus, primo visu differt ; murino-fulvus ; rostro toto, 
pedibus, partibusque omnibus infertoribus flavo-albis ; cauda lined fuscd angus- 
tatd nec ad apicem porrectd supra notatd. Long. 3%, caud@ 2, manis 3, pedis 
5, auricule fere 4. 
Hasrrat.—aArizona. 
(No. 9886, 2.) —On comparing this animal with typical dencogaster from 
Kansas and Nebraska, the differences in general form are obyious. Truly 
Onychomys, with the unmistakable aspect of that section, yet the members are 
