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 I have 
shown in the Hore Entomologice, p. 403; but the remarkable 
relation existing between the larve 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 Pteromys. We have seen that the 
Marsupial Animals do not enjoy any distinct form*, but serve 
* “Les Marsupiaux que nous rangeons & la fin des carnassiers, comme une qua- 
triéme famille de ce grand ordre, pourraient presque former une ordre 4 part, tant ils 
offrent de singularités dans leur économie. Malgré une ressemblance générale de leurs 
espéces entre elles, tellement frappante, que l’on n’en a fait long-temps qu’un seul genre, 
elles différent si fort par les dents, par les organes de la digestion, et par les pieds, que si 
Pon s’en tenait rigoureusement a ces caractéres, il faudrait les répartir entre divers ordres. 
Ils nous font passer par nuances insensibles des carnassiers aux rongeurs.” Régne 
Animal, vol.i. p. 169 & 170. 
VOL. XVI. G merely 
