270 PROCEEDINGS OF THE ACADEMY OF 



same types, and therefore diagnostic of the combined tj-pes. All 

 the cliaracters are referable to the following categories: 



1st. Cliaracters differentiating the Manatee from tlie Cetaceans, 

 which (after proper restrictions) are granted, and more tlian 

 granted. 



2d. Characters common to generalized and quadruped mammals, 

 and therefore not distinctive. 



3d. Characters confined to distant isolated and specialized types 

 of subordinate value, and whose very isolation and specialization 

 are evidence of their slight taxonomic significance. 



There is not a question or alternatives, as might be supposed 

 from the arguments noticed, between the Cetaceans or the Pach^-- 

 derms. Even if all the differences urged as distinctive of the 

 Sirenians from the Cetaceans were conceded, the views here 

 advocated that the Sirenians are a distinct order would loom 

 forth in proportionately more imposing form, but such differences 

 cannot be cast into the scale of the Pach3'derms, as evidences of 

 affinity with them, since tliey are of either a more generalized or 

 specialized value. 



The Sirenians not Pachyderms. 



In view of these facts, it seems evident that we must answer 

 the question proposed ("From these differences must we not 

 remove the Manatus from Cetacea and place it among Pachy- 

 dermata, where it stands in the same relation as do the seals 

 among the other Carnivora?") decidedly in the negative as to the 

 latter and capital clause (but affirmatively as to the former and 

 subordinate one). This we are more prepared to do after having 

 ascertained that the advocate who has found no characters com- 

 mon and confined to the Manatee and the Pachyderms ha"S found 

 several characters common to and confined to the Manatee and the 

 Cetaceans. 



It may be added, too, that some of the characters which are, in 

 a measure, shared b}' peculiar forms of Sirenians and Ungulates 

 are adaptive or tcleological modifications, having reference, how- 

 ever, to analogous rather than identical ends, and even requiring 

 some effort of the imagination to detect the resemblance supposed 

 to exist. They are special characters gained by highly modified 

 forms, whose well-ascertained affinities forbid the idea of tlieir 



