1864. | DR. J. &. GRAY ON BRITISH CETACEA. 229 
Second and Third Cervical Vertebre of Balenoptera rostrata, united by the 
, crural arch. 
Extreme width 12 inches; height 6 inches. Articular suface: width 4 inches. 
Fig. 22. 
Fifth Cervical Vertebra of Balenoptera rostrata. 
The careful examination of many skeletons has proved to me 
that almost every bone of each genus is peculiar—that is to say, that 
no bone is exactly alike in any two genera; but the difference be- 
tween them is often very slight, so slight that it would be almost im- 
possible to convey an accurate conception of it to the reader by words 
alone, yet it is permanent and characteristic. Though the same 
bones of the different skeletons of the same species of Megaptera or 
Physalus, which I have examined, offer a certain amount of variation 
in minor particulars, yet almost every bone of each species has a 
character of its own; so that a person conversant with the subject, 
and fresh from the study and comparison, can say at once to which 
