XXX INTEODTTCTIOIf. 



In all species of Chiroptera the testes pass periodically into a 

 temporary scrotum formed out of the skin of the perinoeum (see 

 Plate XIII. tig. 1). 



The preputium clitoridis is long in the species of the EmbaUo- 

 nurine alhance, and appears to reach the greatest development in 

 Noctilio (see p. 393), in which it is nearly as long as the penis of 

 the males. In the species also included in this alliance the open- 

 ing of the vulvae is longitudinal; whereas in the Vespertilioniue 

 alliance and in the Megachiroptera the vulvte open transversely, 

 and the preputium clitoridis is short. In Oheiromeles torquatus and 

 in Noctilio Jeporinus the clitoris is perforated by the urethra. 



The form of the uterus varies considerably in different genera, 

 and even in different species of the same genus. 



In Megachiroptera the uterus is deeply divided into two cornua, 

 which extend almost to the os uteri. Externally the body of the 

 uterus appears to be nearly as long as the cornua ; but this is due to 

 the union of the adjoinmg sides of the cornua forming a common 

 septum. 



In Microchiroptera the cornua are very long in many species — ■ 

 Megaderma spasma and Phyllorliina speoris, e. g., where the uterus 

 externally resembles that of the Megachiroptera ; but I have not 

 found the internal septum carrying the cornua almost to the os uteri 

 as described above, and the body of the uterus is much longer. In 

 other species {ScotopJiilus temminckii, Miniopterus schreihersii, Tapho- 

 zous nudiventris, and Molossus abrasus, e. g.), the body of the uterus 

 is still longer, almost as long as the cornua. In Corinorhinus 

 macrotis the uterus is club-shaped, with two broad and short horns ; 

 while in the far-removed species Vesperugo serotinus and Artibeus 

 planirostris the uteri agree in their simple and undivided condition. 



Geogkaphic^l Disteibotion. 

 Although most abundant in the tropics and in the warmer parts 

 of the temperate zones of both Hemispheres, representatives of the 

 order are to be found in every region where flying insects abound, 

 extending even to the confines of the Arctic Circle. No Bats have 

 been found in Iceland, in St. Helena, in the Galapagos Archi- 

 pelago*, or in Kerguelen Land, nor do they appear to inhabit any of 



* In reply to my inquiries Mr. Darwin has very kindly given me the follow- 

 ing information: — " With respect to Bats at the Galapagos, I would assuredly 

 have recorded their presence had any been seen. Of course it does not follow 

 from this that there are none ; yet, as I never collected in any place with so 

 few insects, it is probable the Bats are really absent." 



