NO. 5 MAMMALS OF PANAMA GOLDMAX 211 



in size, while in the latter species the fourth lower premolar is fully 

 twice the size of the first lower molar, and half again as large as the 

 third lower premolar. Thomas further remarks that " in spite of 

 their general resemblance to each other the difference in the propor- 

 tions of the lower teeth seems to necessitate the distinction of the 

 Central-American Diphylla from that of Brazil." The forearm 

 measurement given is 54 millimeters. Specimens of Diphylla from 

 as far north as southern Mexico may prove to be referable to this 

 species. 



Family NATALIDAE 



The members of the family are small, delicately formed bats, the 

 continental representatives of which are recognizable by peculiar, 

 low, somewhat funnel-shaped ears, long, slender limbs, large inter- 

 femoral membrane and the absence of nose leaves. The skull is long 

 and narrow, with high subglobose braincase ; the palate is excised 

 anteriorly, but the premaxillse meet in the median line in front of two 

 well-developed foramina ; postorbital processes are absent. 



Genus NATALUS Gray 

 Salient characters of the only known continental genus of this 

 restricted gro"up have been given under the" family. In addition, the 

 long, thread-like tail crosses the inter femoral membrane, which is 

 naked, except for a thin line of fringing hairs along the posterior 

 margin. The teeth are 38 in number. 



NATALUS MEXICANUS Miller 



Mexican Straw-colored Bat 



Nafalus mexicanus Miller, Proc. Acad. Sci. Philadelphia, p. 399, September 

 12, 1902. Type from Santa Anita, Lower California, Mexico. 



Rich golden yellow appears to be the normal color of Natalus 

 mexicanus, but individuals vary to dark brown. The color in con- 



Fig. 18.— Natalus mexicanus. 

 No. 521 1 7, U. S. Nat. Mus. About nat. size. 



junction with the thin papery ears and flying membranes will aid in 

 identification of the species. Its occurrence in Panama is known 

 only from the record by Allen (1904, p. 78) of a single specimen 



