406 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



and sharply bicolored tail, as well as by its longer fur at all seasons. 

 The skull of P. mearnsii is smaller, and has a more swollen brain- 

 case, shorter and more depressed rostrum, and shorter pterygoid 

 fossa and interpterygoid notch. The dentition also is perhaps a 

 little heavier. Compared with P leucopus, the skull is lower and 

 more slender, with a corresponding shortening of the brain-case, 

 pterygoid fossa, and rostrum. In the vicinity of San Antonio, Texas, 

 Peromyscus texanus and P. michiganensis paUescens occur together. 



Doctor Woodhouse states, in both his preliminary and final descrip- 

 tions of this mouse, that his type came from western Texas, on the 

 Rio Grande, near El Paso. I have examined the alcoholic type 

 (No. hVuV? U.S.N.M.) and another specimen (No. sVtA U.S.N.M.), 

 labeled in Professor Baird's handwriting " Hesperomys texana. W. 

 Texas. Dr.- Woodhouse." These two specimens belong to one spe- 

 cies, the same described above. ' Both contained skulls, which were 

 removed for examination, and are now preserved separately. When 

 describing Peromyscus tornillo, I compared it with the types of 

 Hesperomys texana Woodhouse, but the skulls were comminuted 

 and the skins practically undeterminable from long immersion in 

 spirits. Finding them to be different from tomUlo, and being 

 misled by the small size of the teeth and imperfectly cleaned 

 rostrum of the type of texanus, I mistook the latter for the mouse 

 which Mr. W'ilfred H. Osgood has named Peromyscus sonoriensis 

 ilandus. Mr. Osgood has since carefully cleaned the rostral frag- 

 ments of the type skull of texanus, and discovered that it is a mem- 

 ber of thQ leucopus group, but very different from tornillo, the only 

 member of that group known from the region near El Paso. As the 

 teeth, mandible, and rostrum are exactly like those of the form 

 which I had named canus, from Fort Clark, Kinney County, Texas, 

 it is quite certain that the type of texanus was obtained in the 

 Middle Texan Tract, which was crossed by Doctor Woodhouse, and 

 that it is identical with canus. 



Habits and local distribution. — The Texas gray mouse is a» inhab- 

 itant of woodland near streams, and is abundant in such places 

 throughout the Middle Texas Tract. The number of young, deter- 

 mined by dissection, in one specimen (January 12), was five. 



