Structure and Oeconomy of Whales. 375 
probably from twenty to fifty feet long ; under this denomi- 
nation there is a number of fpecies. 
From my want of knowledge of the different genera of this 
tribe of animals, an incorredlnefs in the application of the 
anatomical account to the proper genus may be the confe- 
quence ; for when they are of a certain fize, they are brought 
to us as Porpoifes ; when larger, they are called Grampus, or 
Fin-fffh. A tolerably correct anatomical defcription of each 
fpecies, with an accurate Drawing of the external form, 
would lead us to a knowledge of the different genera, and 
the fpecies in each ; and, in order to forward fo ufeful a work, 
I propofe, at fome future period, to lay before the Society 
defcriptions and drawings of thofe which have come under my 
own obfervation. 
From fome circumftances in their digeftive organs we 
fhould be led to fuppofe, that they were nearly allied to each 
other ; and that there was not the fame variety, in this refpedf, 
as in land animals. 
In the defcription of this order of animals, I fhall always 
keep in view their analogy to land animals, and to fuch as occa- 
fionally inhabit the water, as white Bears, Seals, Manatees, 
&c. with the differences that occur. This mode of referring 
them to other animals, better known, will aflift the mind in 
underftanding the prefent fubjeft. It is not, however, intended in 
this Paper to give a particular account of the ftru&ure of all 
the animals of this order, which I have had an opportunity of 
examining : I propofe, at prefent, chiefly to confine myfelf to 
general principles, giving the great outlines as far as I am 
acquainted with them, minutenefs being only neceflary in the 
inveftigation of particular parts. 
Vol. LXXVII. 
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