602 Bulletin American Museum of Natural History. [Vol. XIX, 



hispidus, as, respectively, Sigmodon arizoncs and S. a. major, 

 with which perhaps 5. baileyi should be associated. Named 

 for Mr. Vernon Bailey, who has done so much to establish 

 order in this very puzzling group. 



14. Reithrodontomys megalotis sestinensis, subsp. nov. 



Type, No. 21175, 3 ad., Rio Sestin (altitude, 7500 feet), northwest- 

 ern Durango, April n; J. H Batty. 



Similar in general coloration to R. megalotis, but upper parts more 

 strongly varied with black and less fulvous, and with relatively longer 

 tail. Type, total length, 139; head and body, 70; tail vertebrae, 69; 

 hind foot, 18; ear (from notch), 14. An adult female: 139, 69, 70, 

 18, 14. 



Represented by 4 specimens taken as follows: Rosario, i, Jan. 25; 

 Rio Sestin, 3, April 11-15. 



The white underparts and much smaller size distinguish this 

 form from R. m. obscurus Merriam, from near Guadalupe y 

 Calvo, Chihuahua, on the western side of the Sierra Madre. 

 While similar in size to R. m. deserti Allen, from Nye County, 

 Nevada, it differs from it in much darker coloration. 



15. Neotoma intermedia durangae, subsp. nov. 



Type, No. 21185, ^ a d-, San Gabriel (altitude, 7000 feet), north- 

 western Durango, Feb. 20; J. H. Batty. 



Externally similar to Neotoma intermedia albigula Hartley, but 

 averaging rather larger, with a shorter and broader skull and much 

 heavier dentition. 



Measurements. Type, total length, 356; head and body, 197; 

 tail vertebras, 159; hind foot, without claws, 32, with claws, 33; ear, 

 from notch, 30, from crown in dry skin, 25. Four additional males: 

 Total length, 345 (330-356); tail vertebras, 156.5 (152-162); hind 

 foot, 32 ; ear from notch, 29.5 (29-30). Skull, total length, 45 ; basilar 

 length of Hensel, 38; length of nasals, 18; zygomatic breadth, 24; 

 width of braincase at posterior base of zygoma, 18.5 ; mastoid breadth, 

 18; interorbital breadth, 6; length of upper toothrow, 9. 



Represented by 21 specimens, collected as follows: Mt. San Gabriel, 

 9, Feb. 18-20; Rancho Santuario, 6, Feb. 2224 and March 6; La 

 Cienega'de las Vacas, i, March 30; Rancho Bailon, 4, May 10; Arroyo 

 de Bucy, i, May 24. 



Compared with a good series of topotypes of N. intermedia 

 albigula, the skull of N. i. durangcs averages about 2 mm. 



