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V. An Attempt to improve the Natural Arrangement of the 

 Genera of Bat, from actual 'Examination; txnth some Obser- 

 vations on the Development of their Wings. By J. E. Gray, 

 Esq. F.G.S. M.B.S.L. M.Z.S.Sfc.* 



IN the Zoological Journal, vol. ii. p. 242. some time ago 

 I attempted to divide the Bat into two natural groups ; and 

 these groups have been adopted, without acknowledgement, 

 by M. Lesson in his Ma?iucl. But since that time having had 

 the opportunity of personally examining several genera which 

 I had not then seen, and having profited by the observation 

 which Temminck has made on the variations which take 

 place in the number of the cutting and other teeth of Bats, 

 -which I have the power of verifying myself, I have been in- 

 duced to study again the characters of the genera and their 

 groups : and in the hopes of facilitating the study of this uni- 

 versally acknowledged difficult subject I send you an abridge- 

 ment of my observations. The genera of Bats have been al- 

 most entirely formed from the study of the number and posi- 

 tion of the cutting teeth and grinders. Temminck has lately 

 proved, by the examination of several specimens in different 

 stages of growth of the same species, that these characters 

 chiefly depend on the age of the individual examined ; and by 

 this means he has been enabled to abolish several of the ge- 

 nera established by GeofFroy, and acknowledged by the other 

 French naturalists : and I have been enabled, by the oppor- 

 tunities which I have had of examining several of the speci- 

 mens which served Dr. Leach as the type of his new genera, 

 to arrange them with their allies, and in most instances to 

 prove that their advancement to the rank of genera was owing 

 to their being examined in a dry state, and to the particular 

 age of the specimens under examination. The French natura- 

 lists have paid some attention to the peculiar form of the ears 

 of some of the Bats, — an oi'gan which appears to give most ex- 

 cellent characters : but their descriptions have been very vague, 

 certainly not taken from the examination and comparison of 

 the ears of the various genera; for thus, in Desmarest's de- 

 scription of the ear of the genus Ni/ctinomus and Molossus, he 

 must have mistaken the lobule for the tragus or oreillon, and 

 have overlooked the true tragus, which is certainly very small, 

 and sometimes nearly wanting, but very similar to those of the 

 genus Noctilio, where he has correctly described them ; and 

 in the genus Glossophaga, the description of the ears has been 

 entirely omitted. 



Several genera have been established on a slight variation in 



* Communicated by the Author. 



the 



