of certain Birds of Cuba. 41 



passing from the viviparous quadruped structure, approaches 

 to that of the oviparous quadrupeds. And it would be an inter- 

 esting subject of inquiry to know, whether the affinity of trans- 

 ultation in the sub-kingdom of Annulosa takes place in a similar 

 way. In Annulose animals, all relations of this kind are usually 

 concealed by Nature under the mask of metamorphosis, as 1 have 

 shown in the Horce Entomologica, p. 403 ; but the remarkable 

 relation existing between the larvae of Neuroptera, such as Myr- 

 meleon, has not escaped the notice of naturalists. 



The circumstance most deserving of remark in Mammalia, — 

 although it may possibly be the same in all the typical groups of 

 the sub-kingdoms, — is, that the affinities of transultation, which 

 are only visible in smaller groups by means of one or two spe- 

 cies, become here visible by means of whole groups of animals. 

 This, instead of rendering, as might have been expected, such 

 intricate relations more easily understood, has in fact been the 

 great obstacle to the natural arrangement of the class. 



We are by this time, I trust, in some degree enabled to discuss 

 the third subject : namely, what Mammalia make the nearest 

 approach to Birds, and what Birds make the nearest approach 

 to Mammalia ? ^ 



There are three kinds of quadrupeds that possess the power of 

 flight, — Bats, Marsupial Animals of the genus Petaurus, and 

 Glirine Animals of the genus Fteromys. We have seen that the 

 Marsupial Animals do not enjoy any distinct form*, but serve 



* " Les Marsupiaux que nous rangeons k la fin des carnassiers, comme une qua- 

 tri^me famille de ce grand ordre, pourraient presque former une ordre k part, tant ils 

 offrent de singularit6s dans leur Economic. Malgre une ressemblance g6n6rale de feurs 

 esp^ces entre elles, tellement frappante, que Ton n'en a fait long-temps qu'un seul genre, 

 dies different si fort par les dents, par les organes de la digestion, et par les pieds, que si 

 Ton s'en tenait rigoureusement a ces caract^res, il faudrait les r^partir entre divers ordres. 

 Ils nous font passer par nuances insensibles des carnassiers aux rongeurs," Rlgne 

 Animal, vol. i. p. 169 & 170. 



VOL. XVI. G merely 



