326 Agassiz’s Contributions to the 
stated distinctly, that in such cases generic and specific characters are 
identi 
4. Famihes.—Professor Agassiz, in his section on Families, 
explains at length that form is not the characteristic at the basis 
of Classes, Orders, or Genera. He shows that the Classes and 
Whales for example among Mammals, of Sharks and Eels among 
Fishes, of Lobsters and Barnacles among Crustacea, of Butter- 
flies and Beetles among Insects, and so on. Again, form is not 
the fundamental characteristic of Genera; for in related genera 
there is little distinction of this nature. e asks: 
“Do, for instance, the genera of Ursina, the Bears, the Badgers, Y 
Do the Phocoide, the Del- 
the Picinz, the 
Seolopacine, the Chelonioide, the Geckonina, the Colubrina, | 
roide, the Elaterids, the Pyralidoidw, the Echinoide, etc., 
es of one genus when com- 
dif 
Family groups. kind 
“Unless, then, form be too vague an element to characterize pra 
of natural groups in the animal kingdom, it must constitute a props “ies 
feature of families. I have already remarked, that orders ~a 
are the groups upon which zodlogists are least agreed, and to Does this 
and characterizing of which they have paid least attention. ae 
not arise mel. from the fact, that, on the one hand, the ie 
tween ordinal and class ¢ has not been understood, an 
