V-- 



Vol. XXII, pp. 43-44 March 10, 1909 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



TWO NEW BATS FROM THE SOUTHWESTERN UNITED _^ 



STATES. 



BY N. HOLLISTER. 



In the Biological Survey collection are two undescril)ed species 

 of Ml/Otis, rein-esented by specimens from near Needles, Cali- 

 fornia, and the mountains of New Mexico. Both are interesting 

 from the fact that they exhibit a tendency toward the crowding 

 out of the middle upper premolar, an unusual condition in this 

 genus. Six out of the eight skulls examined lack this particular 

 tooth. The specimens were collected during the course of field 

 work for the Biological Survey. 



Myotis occultus sp. nov. 



Type from west side of Colorado River ten miles above Needles, Cali- 

 fornia. No. 137,098 U. S. National Museum, Biological Survey Collection, 

 c? adult, skin and skull. May 14, 1905. N. Hollister. Original No. 2237. 



General characters. — Nearest to M. peninsularis but smaller; forearm 

 shorter; ears smaller; tragus shorter with blunt tij). Calcar longer than 

 free border of interfemoral membrane, which is nearly naked ; wing from 

 near base of toes. 



Color. — Back rich glossy brown, nearest to Front's brown of Ridgway 

 but with a cinnamon tint; face and underparts much paler with decided 

 huffy cast; ears and membranes brown. 



Skull. — Nearest to 3f. peninsularis but smaller; braincase much flatter; 

 rostrum flat and wide. Diflers also from all other North American species 

 of Myotis in its low, flat braincase and relatively wide, flat rostrum. One 

 of the two specimens, the type, lacks the middle upper premolar of Myotis 

 as heretofore diagnosed, leaving the normal dentition of the species some- 

 what in doubt. 



Measurements of type. — Total length, 9(5; tail vertebrae, 40; foot, 10.5; 

 tibia, 14; thumb, 6; tragus, 6.5. Skull: Condylobasal length, 14.2; 

 zygomatic breadth, 9.5; breadth of braincase, 7.8; interorbital constric- 

 tion, 4; maxillary toothrow, 5.9. 



5— Proc. Biol. Soc. Wash., Vol. XXII, igo9. (4o) 



