Natural History of the United States. 251 



tails of structure. Unfortunately many naturalists are deficient 

 in this. Hence they regard a good natural genus such as a mind 

 like that of Linnaeus could found, not as one, but as several ; their 

 menial virion not enabling them to see the whole of it at once, 

 though they can see little trifling distinctions. They break it up, 

 attach names to the fragments, and believe themselves discrimi- 

 nating interpreters of nature, until the discovery of a few more 

 species or the glance of some higher intellect throws the whole 

 again into one, and nothing remains except a shoal of obsolete 

 synonymes, against which young students may wreck themselves. 

 We could fill our pages with instances, but it is better not to enter 

 into particulars. The subject is, however, so important to the 

 progress, and especially to the diffusion of science, that it demands 

 at least an energetic protest against the genus-makers as a body. 

 We are glad to see in some good modern text books, as in Wood- 

 naid's Mollusca, many useless genera restored to their proper 

 places. 



6. Species. — In this most important department of the subject 

 a large number of naturalists will at once join issue with Agassiz ; 

 and we think that the interests of truth demand a careful sifting 

 of the views put forth, not only in the short section under this 

 head, but also in the introductory chapters. The general defini- 

 tion, which we have already quoted, is so vague in its terms that 

 it hardly serves to give the author's view. The "relations of in- 

 dividuals to each other" may, for instance, mean much or very 

 little ; and on the interpretation of this expression hangs the 

 whole question herein dispute between Agassiz and other natural- 

 ists. The precise view intended to be conveyed may perhaps be 

 best gathered from the following passages : — 



"The species is an ideal entity, as much as the genus, the fami- 

 ly, the order, the class, or the type ; it continues to exist, while 

 its representatives die, generation after generation. But these 

 representatives do not simply represent what is specific in the 

 individual, they exhibit and reproduce in the same manner, 

 generation after generation, all that is generic in them, all that 

 characterises the family, the order, the class, the branch, with the 

 same fullness, the same constancy, the same precision. Species 

 then exist in nature in the same manner as any other groups, 

 they are quite as ideal in their mode of existence as genera, fami- 

 lies, etc., or quite as real. But individuals truly exist in a differ- 

 ent way ; no one of them exhibits at one time all the character- 



