XXVlll INTRODUCTION. 



back beneath is well covered witli fur, the overlying wing-membrane 

 is naked. In Pteropus melanopogon and its allies, and in Vespertilio 

 macrotarsus and V. pilosus, the membranes arise near the spine. 



The development of the interfemoral membrane is evidently re- 

 lated to the nature of the food, as it reaches its greatest size in the 

 insectivorous, but in nearly all the frugivorous and sanguivorous 

 species is deeply cut out behind, or forms a narrow projection along 

 the legs. Thus it is well developed in the families Bhinolojphidce, 

 Nycteridce, Vespertilioniclce, Emballonuridce (except in Jthinopoma, 

 believed to be partially if not wholly frugivorous), and in the in- 

 sectivorous species of Fhyllostomidce ; while in the frugivorous and 

 sanguivorous species of the same family, and in the Megachiroptera, 

 it is very small or rudimentary. 



In the insectivorous species it appears not only to aid their rapid 

 doubling motions when in pursuit of their insect prey by acting as 

 a rudder on the air (see p. 403), but also to assist them in the cap- 

 ture and retention of the larger insects, such as the smooth-bodied 

 Coleoptera, as it becomes, when pressed forwards by the tail upon 

 the abdomen, a very effective trap. Its small size in the frugivorous 

 and sanguivorous species which do not require it, to which, indeed, its 

 presence would be actually injurious as impeding their motions when 

 searching for food when suspended by their feet, is easily understood, 

 (See remarks on the interfemoral membrane of Molossi at p. 403, and 

 on that of one of the frugivorous species of Phyllostomidce at p. 503.) 



Odoriferous glands and pouches opening on the surface of the 

 outer skin are developed in many species, but in most cases more 

 so in males than in females, and so constitute very remarkable 

 secondary sexual characters. They are chiefly found in the highly 

 organized forms, as in the larger species of Megachiroptera, in the 

 subfamily Phyllorhinince {RhinolopMdce), in the groups Vampyri and 

 Stenodei-mata (Phyllostomidce), and in the family Emhallonuridce^ 

 They may be classed as : — 



1. Prontal pouches (Phyllorhina, p. 127, PI. IX. fig. 3). 



2. Gular glands and pouches (Tapthozous, p. 378 ; Cheiromeles, 

 p. 405, PL XXI. ; Molossus, p. 410, Pis. XXI., XXII. ; Phyllostoma, 

 p. 484). 



3. Shoulder-pouches and glands (Epomophorus, p. 5, Pi. II. fig. 3 ; 

 Pteropus, p. 16 ; Cynonycteris, p. 74). 



4. Thoracic glands (Ametrida, p. 531, PL XXX. fig. 2). 



5. Pubic and anal glands and follicles (RhinolopMdce, p. 99 ; 

 Megadenna, p. 154 ; NodUio, p. 303 ; Eonyden's, p. 95). 



