FAMILIES. 237 



having a common character, as, for instance, when it is 

 said of Zoophytes that they have a radiated form ; there, 

 it indicates any outline which circumscribes the body of 

 animals, when, for instance, animal forms are alluded to 

 in general, instead of designating them simply as animals ; 

 here, again, it means the special figure of some indivi- 

 dual species. There is, in fact, no group of the animal 

 kingdom, however extensive or however limited, from the 

 branches down to the species, in which form it is not 

 occasionally alluded to as characteristic. Speaking of 

 Articulates, C. E. v. Baer characterizes them as the type 

 with elongated forms, Mollusks as the type with massive, 

 forms, Eadiates as that with peripheric symmetry, Verte- 

 brates as that with double symmetry; evidently taking 

 their form, in its widest sense, as expressing the most 

 general relations of the different dimensions of the body 

 to one another. Cuvier speaks of form in general, with 

 reference to these four great types, as a sort of mould, as 

 it were, in which the different types would seem to have 

 been cast. Again, form is alluded to in characterizing 

 orders; for instance, in the distinction between the Bra- 

 chyourans and the Macrourans among the Crustacea, or 

 between the Saurians, the Ophidians, and the Chelonians. 

 It is mentioned as a distinguishing feature in many 

 families, ex. gr. the Cetacea, the Bats, etc. Some genera 

 are separated from others in the same family on the 

 ground of differences of form ; and in almost every de- 

 scription of species, especially when they are considered 

 isolatedly, the form is described at full length. Is there 

 not, in this indiscriminate use of the term form, a con- 

 fusion of ideas, a want of precision in the estimation of 

 what ought to be called form, and what might be desig- 

 nated by another name ? Such seems to me to be the case. 



