rJ6 



CHAPTER XXIX. 



MULTUNGULA COIltill 1(0(1 SIRENIA DIXOTHERUM MANATEE DrooXG RHYTINA. 



Following Professor Owen's classification, which is in this respect that of Cuvier, I shonld 

 now pass on to a new section which he designates " Mutilata," and which is composed of the 

 SiRENiA and Cetacea. But tlic affinity of the Sirbnia to the Paclijrdermata appears to me so 

 much greater than to the Cetacea that I exercise tlie option I reserved to myself of following a 

 different arrangement from his in cases where my own con^ictions were very decidedly opposed 

 to the arrangement he adopted. In this case I cannot say that my convictions are opposed to his, 

 because he has in many places* stated that he had arrived at the conclusion that the Sirenia 

 constitute an order of mammals quite distinct from the Cetacea, and in some characters more nearly 

 allied to the Pachyderms ; notwithstanding which, he, in his well-considered sj'stom of arrange- 

 ment, removes them from the Pachyderms and places them in the same section as the Whales. In 

 one sense, it may be said that the matter is not of much importance, because, if ■s^e bring the 

 Cetacea after the Pachydermata, and place the Sirenia at the head of the former, their position 

 in the arrangement is the same in either \'iew. In another sense, however, it is of very consi- 

 derable imiDortance, because there is involved in it the question whether they are more nearly 

 allied to the one or the other ; to speak in a general way whether they are modified Whales or 

 modified Elephants. I think they are modified Elej^hants. Moreover, although we may place 

 the Whales after the Elephants, it cannot be said that that is on account any close affinity between 

 them. The Cetacea form a group ap)art. The thread breaks when we come to them, and we 

 must begin a new piece ; but with the Sirenia it is not so, the thread between the Elephants 

 and them is still continuous. 



The mal-association in Professor Owen's arrangement is due to greater weight being given 

 to the form and purpose of the structure of the animal than to the p/aii of the structure. On 

 this point the ideas of Agassiz seem right in principle. The form and purpose to which they are 

 to be put are subordinate to the great jikin of the work, and affinities founded upon the congruity 

 of the former .should certainly give way to those founded upon the analogy of the latter. Not 

 to speak of more widely separated organisms, the form of the Whale and the pui-pose for which 

 its form is given is the same as that of a fish, namely, to live in water instead of air, but the plan 

 of their sti'ucture is diffoi'cnt. The purpose of the structure of the bat is the same as that of 

 the bii-d, but its plan is different. 



Agassiz, in stating his views of the position of classes, orders, and families, takes the p/nii of 

 structure as the character for distinguishing the great divisions of the organic kingdom, called by 



* Owen in " Proc. Zool. Soc." 1838, p. 45, &c. 



