444 PROCEEDINGS OF THE ACADEMY OF [April^ 



From M. mexicanus and M. huUeri, californicus can be distinguished 

 by the characters given in the key. 



The Cape St. Lucas specimens are shghtly differentiated from the 

 typical Yuma specimens, but the differences are so extremely shght 

 that they would not justify the separation of the Cape series. 



Specimens Examined.— YiiXy-mnQ; twenty-one skins, thirty-three- 

 alcoholic individuals : 



Yuma, Arizona. Five. (Biol. Surv.) 



Thirty-five miles east of Yuma, Arizona. Two. (U. S. N. M.) 



Parker, Yuma coimty, Arizona. One. (U. S. N. M.) 



San Xavier, Pima county, Arizona. One. (U. S. N. M.) 



Ai-izona. Five. (A. M. N. H.) 



Tombstone, Cochise coimty, Arizona. Two. (Biol. Surv.) 



Vallecito, San Diego county, California. Seventeen. (Biol. Surv. 

 and U. S. N. M.) 



De Luz, San Diego county, Cahfornia. Two. (Biol. Surv.) 



Indian Wells, San Diego coimty, Cahfornia. Four. (U. S. N. M.) 



Ortiz, Sonora, Mexico. One. (Biol. Surv.) 



Camoa, Sonora, Mexico. Eleven. (Biol. Surv.) 



Cape St. Lucas, Lower Cahfornia. Eight. (A. N. S. Phila. and 

 U. S. N. M.) 



Macrotus pygmseus n. sp. 



Type.—MvM skin and skuh; Izamal, Yucatan. No. 12,756] 11, 043,. 

 American Museum of Natural History. Collected by George F.. 

 Gaumer. 



Distribution. — Ivnown only from the type locality. 



General Characters. — Size extremely small (for the genus) ; skull with 

 the interorbital region very broad and distinctly flattened ; teeth large 

 and strongly crowded. 



Head. — Ear rounded ; internal margin evenly arcuate ; apex rounded 

 with but a slight trace of an angle; external margin evenly arcuate, 

 basal notch very slight, basal lobe subobsolete ; transverse plicse dis- 

 tinct; interauricular membrane distinct and moderately high; tragus 

 lanceolate, apex rather blimt, external margin with a slight basal 

 accessory longitudinal lobule. Nose-leaf high, lanceolate, with the 

 nose-pad over twice as high as the width of the pad; apex rather 

 acute; nostrils slightly crescentic. Extremity of lower jaw with the 

 triangular pad bearing a shallow mecUan depression. 



Limbs. — Forearm short, robust, evenly arcuate. Thumb rather 

 long, enveloped in membranes for more than half its length. Third- 

 digit moderately long. Posterior hmbs heavy; feet strong and but 

 moderately compressed; calcanea long, stout and compressed. 



