208 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



horses and mules and rather rarely bite human being;s, but since 

 vast areas unoccupied by man are inhabited by them in considerable 

 numbers, they doubtless prey normally upon native mammals or 

 birds. Three genera are known, two of which, Dcsmodus and 

 Diphylla, are represented in Panama. 



Genus DESMODUS Wied 

 Blood-sucking bats met with throughout tropical Middle America 

 usually belong to the genus Desmodus, the other Desmodont genus 

 of the region, Diphylla, being exceedingly rare. Desmodus is dis- 

 tinguishable externally from Diphylla by the longer, more pointed 

 ears, and the long thumb, equal to about one-fifth the length of the 

 third finger, with two prominent pads on the inner side of the meta- 

 carpal. The calcar is short, stumpy, and supports no part of the 

 interfemoral membrane. More important generic characters are 

 lodged in the teeth, which dififer notably in form and are reduced to 

 20 in number. 



DESMODUS ROTUNDUS MURINUS Wagner 



Mexican Vampire Bat 



D[esmodus] murinus Wagner, Schreber's Saugthiere, Suppl., Vol. i, p. 377 

 (1839), 1840. Type from Mexico. 



Although few examples were met with by me the Mexican vampire 

 bat is probably rather common at low elevations throughout Panama. 

 Specimens of Desmodus from Mexico average smaller than those 



Fig. 17. — Desmodus rotundus murinus. 

 No. 179723, U. S. Nat. Mus. About nat. size. 



from Paraguay, assimied to represent typical D. rotundus, and seem 

 referable to a northern race for which the name D. murinus Wagner 

 may be used, as has been shown by Osgood.^ 



The difTerence in size between the northern and southern forms 

 is, however, rather less than might be inferred from measurements 

 by Osgood (/. c). He gives the length of the forearm in typical 

 D. rotundus as 60-64 niillimeters, as against a maximum of 55 milli- 

 meters in Mexican and Guatemalan specimens referred to the north- 



* Pub. Field Mus. Nat. Hist.. Zool. Ser.. Vol. 10, No. 5, p. 63, Jan. 10, 1912. 



