168 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. III. 



width, 16; interorbital constriction, 6.5; width. of interparietal, 

 6.5; length of nasals, 10; anterior width, 3; posterior width, 1.5: 

 greatest breadth of rostrum, 4; palatal arch to alveoli of incisors,. 

 12; greatest width of basioccipital between bullae, 5; mastoid 

 breadth, 15; length of upper tooth row, 4. 



This subspecies while darker than typical P. baileyi is remark- 

 able for its very slender nasals, which cause it to differ from any 

 other known form. It appears to be a coast race, for, although 

 the mountain ranges of San Pedro Martir and Hanson Laguna 

 were thoroughly explored by Mr. Heller no specimen of this 

 race was found among them. It was not uncommon at San 

 Quentin. 



Perognathus femoralis *mesopolius. S.ubsp. nov. 



Type locality. Pefion, San Pedro Martir mountains, Lower 

 California, Mexico, 5,000 feet elevation. 



Geogr. distr. San Pedro Martir mountains, Lower California, 

 Mexico. 



Gen. char. Size large, ear large, hind foot and tail long, 

 similar to femoralis but grayer, lacking the bistre color so char- 

 acteristic of that species. Skull with greater interorbital con- 

 striction and somewhat less mastoid breadth. 



Color. Above pale gray and light buff lined with black; nose 

 and side of face pale buff lined sparingly with black; sides grayer 

 than upper parts; lateral line light buff; under parts, hands and 

 feet pure white; tail and pencil dusky above, white beneath; ears 

 light brown. 



Measurements. Total length, 232; tail vertebrae, 136; hind 

 foot, 27; ear, 14. Skull: occipito-nasal length, 27; Hensel, 18; 

 zygomatic width, 13; mastoid breadth, 13; interorbital constric- 

 tion, 6; palatal arch to alveolus of incisor, 10; length of nasals, 

 10; posterior width of nasals, 2; anterior width of nasals, 3; 

 greatest width of rostrum, 5. 



This form while related to P. femoralis is easily distinguishec 

 from it by the general gray color of the pelage and the absence 

 of bistre. It appears to be restricted to the San Pedro Martii 

 range, which is separated from the Hanson Laguna mountains 

 on the north by a stretch of about fifty miles of broken hills anc 

 me ;as, and a strip of desert, the elevation of this tract ranging 

 from 3,000 to 6,000 feet. In the Hanson Laguna mountains 

 P. femoralis was taken. 



*//e(Jo7roA.zo?, half gray. 



