MURIDAA—SIGMODONTES—ONYCHOMYS., 105 
of a maguey, in a nest built of fibres of ‘zaiate’, containing two little 
ones.” 
This animal, compared with the somewhat smaller and the brighter- 
colored aztecus, bears much the same relations that the large gray californicus 
bears to the deucopus (“gambeli”), with which it is associated in California. 
TaBLE XXIX.—Measurements of three (dry) individuals of H. MELANOPHRYS (=? MEXICANUS, DeS.) from 
Southern Mexico. 
Nose to— 
8 Locality. Collector. 2 & 
EI Eye. | Ear. lace Tail. | z = 8 
A 3 SP eee ia 
10183 | Santa Efigenia-...- F. Sumichrast . ....| 0.62 | 1.12 | 1.40 | 4.15 | 5.00 | 0.42 | 1.04 | 0.78 
10296) |; Tehuaean’-<=—- <2. -\|b=---- Wiese poesia |eosoco basse 1.30 | 4.00 | 4.60 | 0.40 | 1.06 | 0.81 
9511 | Tehuantepec ---....|------ GN Scns oseccullasosoa||sss5ee|/Soooce 3.90 | 4.90 | 0.40 | 0.99 | 0.77 
Norre.—Since writing the preceding, we have examined three other specimens from Tehuantepec, 
which, if the same as the types of melanophrys, lessen the chances that the latter is different from mexi- 
canus. But they differ in many respects from the specimens just enumerated, being so very much smaller 
that we cannot satisfy ourselves of their identity. The tail only exceeds the body in one specimen, and 
here only by little; in the others, it is about as long, relatively, as De Saussure gives for mexicanus. That 
these specimens are not immature is shown by the fact that one®*of them is a nursing female. In color, 
they are almost precisely like the foregoing, but do not show the black ring round the eye, nor the dusky 
spot at base of the metatarsus. One of them is pure white below; another is grayish (it looks as if soiled) ; 
while the third has the faintest possible fulvous tinge all along the under parts. 
Much more material than that now in our possession will be required to determine the limits of 
variation of this large, gray, lewcopus-like mouse of Mexico, aud fix the species upon secure basis. 
Tape XXX.—Measurements of three dried specimens, probably of MELANOPHRYS, Coues (=? MEXICANUS, 
DeS.), but much smaller. 
| 
Number. Locality. Collector. Length.| Tail. Foot. 
9382 Barrio, Tehuantepec . .-....---- LOGS UTONE Shere Aer = Sop cer 3.50 3.20 0. 67 
Ohi) W\esaaSe GW satecos costes cose nsaesd|(sosecs (WS sndSSe-cosscesesnocs 3.20 3. 00 0.70 
CBr llsaheec AG fas Adcictoo, abeuespdacee ss5see GW sesstagbsoasoecescsc 2. 90 3.10 0. 69 
Suscenus ONYCHOMYS, Baird. 2 
Hypudeus sp. MAXIMILIAN, Reise, ete. ii, 1841, 99 (nee auct.). . 
Mus sp. Aup. & Bacu., Q. N. A. ii, 1851, 327. 
Onychomys, Bairp, M. N. A. 1857, 458 (type, Hypudaus leucogaster, Max.).—Cotvers, Proc. Acad. Nat. Sci. 
Phila. 1874, 182. 
Cuars.—Skull strictly as in Hesperomys, but molars larger, with sharper 
salient and reéntrant angles. External form departing from Hesperomys, and 
