Classification of the Mammalia. , 63 



are of a value as great as the organic characters of more expanded 

 orders. 



There are residuary or aberrant forms in some of the orders, 

 which, to the systematist disagreeably, compel modifications of 

 the characters that would apply to the majority of such orders. 

 The flying Lemurs (Galeopitheci), the rodent Lemurs (Cheiromys), 

 the slow Lemurs (Loris, Otolicnus), forbid any generalization as 

 to teeth or nails in the Quadnimana, whilst they continue asso- 

 ciated with that order by the character of the hinder thumb ; 

 which, by the way, they possess in common with the pedimanous 

 Marsupials. The large, volant, frugivorous Bats (Pterojms) are 

 equally opposed to the application of a common dental character 

 to the Cheiroptera. They are associated with the insectivorous 

 Bats on account of the common external form arising out of the 

 modification of their locomotive organs for flight, just as the Du- 

 gongs and Manatees are associated with the Cetacea on account of 

 their resemblance to Fishes arising out of the same modification 

 of the locomotive system for an aquatic existence. The herbivo- 

 rous Cetacea are now separated from the piscivorous Ceiacea as a 

 distinct order ; and with almost as good reason we might sepa- 

 rate the frugivorous from the insectivorous Cheiroptera ; the cases 

 are very neatly parallel. 



Nature, in short, is not so rigid a systematist as Man. There 

 are peculiar conditions of existence which she is pleased shall be 

 enjoyed by 'peculiarly modified mammals ; these peculiarities 

 break through the rules of structure which govern the majority of 

 species existing and subsisting under the more general conditions 

 of existence, to which the larger groups of Mammalia are respec- 

 tively adjusted. 



One class of organs seems to govern one order, another class 

 another order ; the dental system, which is so diversified in the 

 Marsupialia and Bruta, is as remarkable for its degree of con- 

 stancy in the llodentia and Insectivora. But, as a general rule, 

 the characters from the dental, locomotive, and placental systems 

 are more closely correlated in the Gyrencephalous orders than in 

 those in the inferior subclasses of the Mammalia. — Journal Lin- 

 nean Society. 



