406 Zoological Society, 



the largest species of that family ; while in the entire class of Birds, 

 the law as to the size of the blood- corpuscles is the same as in a 

 single order of mammals. 



Therefore, when that eminent inquirer Hewson states that these 

 corpuscles are not larger in the largest animals, citing in support of 

 his argument the Ox and Mouse, it must be understood as applicable 

 only to mammals of different orders. Among the rodents which I 

 have examined, the great species, as the Capybara and the Beaver, 

 have much larger blood- corpuscles than the smallest species, as the 

 Bank Vole and the Harvest Mouse. 



2. Characters of Six new Genera of Bats not hitherto distin- 

 guished. By J. E. Gray, Esq., F.R.S. etc. 



The first four genera belong to the tribe of Phyllostomina, of Nose- 

 leafed Bats. 



1. MiMON. 



Ck. gen. — Membrana interfemoralis magna, truncata. Ala latse, 

 margine anteriore lato, a sumrao talo extenso. Pedes elongati. 

 Crura nuda. Cauda mediocris, inclusa ; apice superiore, mediano. 

 Aures laterales, magnse. Mentum tuberculo parvo utrinque sig- 

 natum ; tuberculis stria angusta divisis. Pollex longus, attenu- 

 atus ; articulis sequalibus. Denies incisores f ; duo medii euperiores 

 magni ; inferiores parvi, stipati. 



Ch. gen. — Interfemoral membrane large, truncated. Wings broad, 

 with a broad front margin from the upper part of the ankle. Feet 

 elongated. Legs bald. Tail moderate, enclosed ; apex superior, 

 medial. Ears lateral, large. Chin with a small tubercle on each 

 side, separated by a narrow groove. Thumb long, slender ; joints 

 equal. Cutting teeth -| ; two middle upper large ; lower small and 

 crowded. 



In the collection at the British Museum there are two species of 

 this genus, viz. 1 . M. Bennettii = Phyllostoma Bennettii, Gray, Mag. 

 Zool. and Bot. vol. ii. p. 6 ; and 2. M. megalotis = Phyllophora mega- 

 lotis. Gray, Ann. and Mag. N. H. 1842, p. 257 ; Voy. Sulphur, t. v. 



fig. 2. 



2. Trachops. 



Ch. gen. — Memhrana interfemoralis magna, truncata. Aloi a summo 

 talo extensse. Pedes osse calcis elongato insignes. Crura nuda. 

 Cauda mediocris, inclusa ; apice superiore, mediano. Aures per- 

 magnae, laterales. Mentum et labia verrucosa, stria Isevis angusta 

 in medio mento. Dentes incisores ^ ; medii superiores magni, lati, 

 incisi ; inferiores irregulariter ordinati. 



Ch. gen. — Interfemoral membrane large, truncated. Wings from 

 the upper part of the ankles. Feet with the heel-bone elongate. Legs 

 bald. Tail moderate, enclosed ; apex superior, medial. Ears very 

 large, lateral. Chin and lips covered with warts ; chin with a narrow 

 smooth groove in front. Cutting teeth ^ ; middle upper large, broad, 

 notched ; lower in an irregular series. 

 Type, T.fuliginosus, 



