REPORT ON ZOOLOGY. 103 



makes a distinct order of the Amphibia. Tiie Munoiremata 

 he considers as a separate class*. 



On a review of the above systems it w\\\ appear how much 

 difference of opinion exists respecting the value of certain groups, 

 more particularly the Cheiroptera, Marsupialia, and Monotre- 

 mata. To the number of those systematists who regard the 

 Cheiroptera as a distinct order, we may add Geoffroy, whose 

 opinion will have weight, when we remember the particular 

 study which for many years he is known to have made of these 

 animals. We may refer to the twelfth and thirteenth Lectures 

 in his Corel's de V Histoire Naturelle des Mammif^res, as pre- 

 senting considerable details respecting the general organization 

 of these animals and their several peculiarities. He regards 

 them as holding an intermediate place between the Quadrumana 

 and JFerce, but requiring to be separated from both. 



The Marsujiialia will continue to perplex us until we can 

 determine the true value of that peculiar character by which 

 they are so remarkably distinguished from all other Mammalia. 

 Is it to controul the characters derived from the organs of mas- 

 tication, digestion, and motion, which maybe referred almost to 

 as many types as there exist genera amongst these animals ? 

 Even adopting that it ought, as most naturalists seem disposed 

 to do, we have still to decide, whether the MarsupiaUa consti- 

 tute merely a peculiar order, or a group of any higher denomi- 

 nation as supposed by Blainville. Although Cuvier has only 

 admitted them to the former, he observes that they might almost 

 be supposed to form a distinct class parallel to that of the ov- 

 dlnaxy Mammalia, and divisible into similar orders. The solu- 

 tion of these difficulties must probably be sought in a more pro- 

 found study of the 7-elative internal organization of these and 

 other Mammalia. This subject has, indeed, for some time al- 

 ready engaged the attention of Geoffroyf^ and luore recently it 

 has been taken up by Messrs. Morgan^ and Owen§. We may 

 reasonably hope that by the combined researches of these emi- 

 nent anatomists, some new light will liefore long be thrown 

 upon the affinities of these singular animals. 



* Since this Report was read, I have seen a sketch of a new arrangement of 

 the Mammalia recently proposed by M. Duvernoy. Like Blainville, he con- 

 siders the MarsupiaUa, (under which series he incliules the Monofremata,') as 

 a group equivalent to the rest of the Mammalia takon together, for which last 

 he retains Blainville 's name of Monodelphes. His orders are very numerous. 

 See L'Institut, No. Ixv. p. 261. 



t See the article Marsupiaux in the Diet, des Sci. Nat., torn. xxix. 



X Linn. Trans., vol. xvi. pp. 61 and 455. 



§ Proceedings of the Zool. Soc. 1831, p. 159; 1833, p. 128. 

 M 2 



