234 U. Ss. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
through the eye, and passing round behind it into the sooty of the chin and throat, enclosing an oblong white patch under the 
eye. Tail as long as the neck and trunk, exclusive of the head; young? with the body almost entirely black. Length to 
occiput, 3.80 ; to root of tail, 16.50; tail to tip, 11.25; fore foot, 1.50; hind foot, 2.20; height of ear, 1.40. 
A much fuller description of this species, as well as of the Virginia possum, will be found in 
the report of the Zoology of the Mexican Boundary Survey ; I only introduce here the specific 
characters of each. 
The present species appears to replace the common possum in Texas and Mexico, as well as 
in California, and has, doubtless, given rise to the impression of the great range of the former 
species, though the two are sufficiently distinct on comparison; the most southern locality I 
have seen is the city of Mexico. 
The Didelphys californica was first described by Bennett from a specimen caught in North- 
western Mexico, and subsequently received other names; the D. breviceps, from the same 
locality, is doubtless identical, as skulls ofthis genus vary remarkably in the same species, 
andthe great length of the tail, given by Bennett as an important character, has been con- 
siderably reduced by the new measurement of the same specimens by Waterhouse. 
The species is probably abundant in California, though I have not been able to examine any 
from that region. : 
a List of specimens. 
Catal’ gue|Correspondi’g) No of Locality. When Whence ob- | Original |Nature of spe-| Collected by— 
number.| No. of skull. |specim’n. collected. tained. number.| —cimen, 
GS as 2 a Se ee City, of Mexico!—_|. - -..s-—~=-£ John, Potts: -.|..---2=- Skin... ¢-<32)eonnad eee 
2 TUSY OG EP Pee yee ee ene Guyapuco, Mex. -)5.3- 3050 Lt. D.N.Couch.|....-.-- Skeleton ...-|_ 2.) 2 
1121 pit) @ | Saas Matamoras .._--- Feb. 1, 1853 |--=.do.....-5 26 Skin ...-..-|.2-.=sseeeee ‘s 
a 7 eS (SS see eee Ree sme emer Pes (ik, SR eet | ern ee Skel. & skulls.| Dr.L.Berlandier, 
1171 US et [feet ae Lower Rio Grande.|..---------- Maj. W.H.Emory|---..--- SEany ease J. H. Clark ... 
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