18/6.] MR. G. E. DOUSON ON THE MOLOSSI. 703 



great dexterity in quickly changing the direction of their flight, as 

 when obliged to double in pursuing their swiftly flying insect prey ; 

 while the extremely expansible lips evidently aid them especially in 

 capturing during rapid flight and in maintaining their hold on the large 

 round-bodied Coleoptera. Of all Bats the Molossi appear especially 

 suited by their peculiar conformation for capturing the most rapidly 

 flying injects, which, no doubt, form the greater portion of their 

 food. Their large and very strong acutely tubercular teeth would 

 enable them to crush with ease the hard armour of the larger 

 Coleoptera. 



Synopsis of the Genera of Molossi. 



a. First toe much larger and thicker than the other toes 



and separable from them ; ears quite separate. 

 a'. Premaxillary bones united; upper incisors \ery 



strong, close together in front 1. Cheiromcles, p. 704. 



b. First and fifth toes much thicker than the other toes ; 



ears united or close together by their inner margins. 



b'. Premaxillary bones united ; upper incisors close to- 

 gether in front 2. Mulosnus, p. 705. 



c'. Premaxillary bones separate or united by cartilage 



only; upper incisors separate in front 3. Nyctinomus, p. 710. 



The genus Cheiromeles is represented by a single species only, 

 which, as I have previously remarked*, appears to be more closely 

 allied to Molossus, which is restricted to America, than to Nycti- 

 nomus, of which several species inhabit the same countries with it. 



The genera Molossus and Nyctinomus are very closelv allied, some 

 species, as Mulossus glaucinus, Wagner, and 21. bonariensis, Peters, 

 forming the connecting links between themf. Nevertheless I retain 

 these genera distinct, as they are convenient for grouping the 

 species, and partly correspond to their geographical distribution, the 

 species of Molossus being confined to America, while those of Nycti- 

 nomus are found in both hemispheres. 



These genera have been divided into several subgenera, which 

 depend on slight differences in dentition and in the form of the ear- 

 conch and tragus. But so many perfectly intermediate forms exist 

 that it is impossible to subdivide Molossus and Nyctinomus, which, 

 indeed, as I have remarked above, may come (o be regarded here- 

 after as subgenera only. Thus M. (Promops) tongimanus resembles 

 M. rvfus (the representative of the subgenus Molossus) closely in 

 the form of the tragus, and in the obtuse not oblicpuely truncated 

 muzzle; and M. (Promops) nasufus, relegated to the subgenus 

 Promops on account of its dentition, in all other respects is much 

 more closely allied to M. rufus, with which it agrees in the peculiar 

 form of the antitragus and tragus, and even in the distribution of 

 the fur; while M. rvfus, which differs from all other species in 

 dentition, shows its close affinity to the representatives of the sub- 



* Monograph of the Asiatic Chiroptera, p. 177. 



t Should the discovery of species even more intermediate than these render 

 ii necessary at any future time to unite the genera Molossus and Nyctinomus, 

 the former name, which has priority, must be used for the single genus. 



