by MM. Van Beneden and Gervais. 195 
distinetions are pointed out by the figures. 
n the same manner, Eschricht did not believe in the exis- 
It is to be remarked that M. Gervais gives no characters by 
which to distinguish the species from each other. We have 
only the habitat of the whale to guide us; and if that is wanting, 
we must read over each of the descriptions; whereas in my 
generic characters the most important characters which dis- 
tinguish the different species may at once n. 
The number of known whales has, since I began the study, 
very greatly increased; and I believe that as yet we do not 
know half of those that exist and are to be distinguished by 
very decided osteological characters. 
It is curious that in this work the whalebone is only slightly 
referred to under one or two species, and never figured; and 
this is the more remarkable as the authors in their titlepage spe- 
cially refer to the dentition of the different species. It is true 
that the whalebone is not the homologue of the teeth of other 
Cetacea, as it was formerly supposed to be; but it forms as 
good characters for the separation of the families, genera, and. 
species as the teeth afford in other mammalia. Indeed it was 
pe LI 
(Agaphelide) ; 3rd, the Hunchbacks (Megapteridze) ; 4th, the 
Finners ( Physalidz) ; 5th, the Pike-whales (Pterobalznidz). 
M 
first rib of some of the common whales, and publishes them 
in the Proceedings of the Academy of Sciences of Brussels, 
1868,p.65. He figures two of these variations—one of Ba- 
lenoptera laticeps, and the other of Phocena — He 
