I7 2 Bulletin American Museum of Natural History. [Vol. XIV, 



appear to be somewhat localized, they often occur together, speci- 

 mens of each being collected at the same localities at practically 

 the'same dates. In the black phase the long overhair is black, 

 but of about the same length and coarseness as the white over- 

 hair in the gray phase. The white overhair is more conspicuous 

 owing to its contrast with the black surface of the underfur. In 

 only a few instances do we meet with a mixed condition in which 

 both coarse black and white hairs are intermixed. In such in- 

 stances the white hair is very scanty and scattered. The gray 

 phase appears to predominate throughout the interior of Mexico, 

 including the whole tableland region, whence very few black speci- 

 mens are represented in the present series. On the other hand, 

 in the lower Rio Grande region of Texas, and along the eastern 

 coast of Mexico, from southern Tamaulipas southward, and along 

 the whole west coast from Guatemala to Mazatlan, the black 

 phase is common, and at some localities appears to predominate. 



Didelphis marsupialis texensis, subsp. nov. 



Type, No. ffHrff, Bio1 - Surv - Co11 - u - s - Nat - Mus -> ^ ad - Brownsville, 

 Texas, April 13, 1892 ; F. B. Armstrong. 



Similar in coloration to D. marsupialis (typica), but with a relatively longer 

 tail, longer nasals, usually terminating posteriorly in an acute angle, instead of 

 being rounded or more or less abruptly truncated on the posterior border. 



Measurements. Type, total length, 820 mm.; head and body, 410; tail, 

 410 ; tarsus, 70 ; ear, 50. Adult males range in total length from about 780 to 

 820 mm., and adult females from about 700 to 730 mm. The ratio of tail 

 length to the length of head and body ranges, in normal specimens, from about 

 85 to 100. (For additional measurements see Table IV.) 



Skull. The nasals, with individual exceptions, terminate posteriorly in a 

 pointed angle, the portion anterior to the point of greatest expansion being as 

 long as, or a little longer than, the anterior half of the basal rhomboid. 



Geographical Distribution. 'Yhe coast region of Texas, from Nueces Bay 

 southward, and the Lower Rio Grande Valley, as far up the valley at least as Del 

 Rio, Val Verde County. Sporadically northward to San Antonio, at which 

 point D. m. texensis occurs with D. virginiana, the latter greatly predominat- 

 ing. It doubtless ranges somewhat to the southward of the Rio Grande, but 

 there are no specimens available for examination from between Brownsville 

 and Tampico. 



Dichromatic, the black phase, in the material examined, prevailing in the 

 ratio of five to one of the gray phase, as shown by the following record of 



Specimens examined : 



Texas : San Antonio, 2, black phase ; Rockport, 3 2 in black phase, I in 



