100 



BULLETIN 144, UNITED STATES NATIONAL MUSEUM 



mally present (lacking on both sides in 2 out of 24 skulls), but it 

 is crowded inward from the tooth row, or sometimes stands quite in 

 the row though closely pressed between the two other premolars. 



Measurements. — For measurements see tables, pages 100 and 101. 



Specimens examined. — Total number 27, from the following locali- 

 ties: 



ARIZONA: Fort Verde, 1 skin (A.M.N.H.) ; Fort Whipple, 1 skin (U.S. 



N.M.); Lakeside, 3 ale. (U.S.N.M.) ; Mojave Desert, 1 skin (U.S.N.M) ; 



Montezuma Well, 1 skin (U.S.N.M.) ; San Francisco Mountain, 1 ale. 



(U.S.N.M.). 

 CALIFORNIA: Imperial County, ten miles above Needles, 1 skin, 1 ale. 



(U.S.N.M.), type of occultus; 4 miles south of Potholes, 1 skin (U.C.) ; 



5 miles northeast of Yuma, 5 skins (U.C). 

 NEW MEXICO : Luna, 3 skins (U.S.N.M.) ; Ruidosa, 1 skin, type of J)aileyi, 



2 ale. (U.S.N.M.) ; Zuni Mts., Bear Ridge, 4 skins (U.S.N.M.). 

 SINALOA: Escuinapa, 1 skin (A.M.N.H.). 



Remm^hs. — The combination of large rostrum, flattened brain case 

 and burnished fur differentiates Myotis occultus very sharply from 

 other American species. Unusually robust cheek teeth are also found 

 in M. velifer but in this animal the brain case is high and the rostrum 

 is less enlarged. Elimination of the second upper unicuspid tooth 

 is here more frequent than in any other known Americaii species. 

 Externally Myotis occultus differs from M. velifer in the glossy fur, 

 ochraceous color of the back, and conspicuously buff underparts. 



The series of specimens now available shows that the characters 

 which Hollister regarded as distinguishing Myotis ha/Ueyi from M. 

 occultus lie within the range of individual variation. 



External measurements of Myotis occultus 



Type of Myotis bailcyi Hollister. 



! Type. 



