726 



MAMMALIA. 



The mammae are two in number, thoracic, generally post- 

 axillary in position. As in Insectivora and Rodentia, the 

 yolk-sac forms a provisional placenta, and the allantoic 

 placenta is discoidal and deciduate. What looks like 

 menstrual flux has been noticed in some bats. In most 

 European bats sexual union occurs in autumn, but the 

 sperms are simply stored in the uterus, for ovulation and 

 fertilisation do not take place till spring — after the winter 

 sleep. In exceptional cases, especially in young forms 

 which were not mature in autumn, pairing occurs in spring. 

 Fossil Chiroptera occur in Upper Eocene strata, but are 

 quite like the modern forms. 



Sub-Order Megachiroptera. 



Sub-Order Microchiroptera. 



Frugivorous bats, usually large. 



The molars have smooth crowns, 

 with a longitudinal groove. 



The thumb is clawed, and generally 

 also the second digit. 



The tail, if present, is below, not 

 bound up with the interfemoral 

 membrane. 



The pyloric part of the stomach is 

 in most cases much elongated. 



Found in warm and tropical parts 

 of the Eastern hemisphere. 



Examples. — 



The "flying-foxes" or fox-bats 

 (Pteropvs), large, tailless bats, 

 distributed from Madagascar 

 to India, Ceylon, Malaya, 

 S. Japan, Australia, Poly- 

 nesia. The largest species 

 (P. edulis) measures 5 ft. 

 across its spread wings. Den- 

 tition, ffif. 



In India, Cynopterus marginatus 

 is very common. Xantliarpyia 

 cegyptiaca inhabits the Pyra- 

 mids. 



Usually insectivorous bats, small 

 in size. 



The molars have cusped crowns, 

 with transverse grooves. 



In the hand the thumb only is 

 clawed. 



The tail, if present, is bound up 

 with the interfemoral membrane, 

 or lies along its upper surface. 



Except in one family the stomach 

 is simple. 



Found in the tropical and temper- 

 ate regions of both hemispheres. 



Examples. — 

 The horseshoe -bats (Rhinolo- 

 phus) ; the common pipistrelle 

 ( Vesperugo pipistrellus) ; the 

 genus Vespertilio, with four 

 British species ; Vampyrus 

 spectrum, a large Brazilian 

 form, which seems to have been 

 erroneously credited with 

 blood-sucking habits ; the 

 common vampire [Desmodus 

 rufus), an American bat — a 

 formidable blood-sucker. 



