OBJECTIONS CONSIDERED. 127 



Now, may I request the reader to mark, in the first place, 

 that what we have specially to deal with at the present stage 

 of the argument are the placoid fishes of the Silurian forma- 

 tion. May I ask him to take note, in the second, that the 

 long-fronted Chondropterygian series of Cuvier, though it in- 

 cludes, as has been already said, the placoid order of Agassiz, 

 — just as the red-blooded division of animals includes the 

 bimana and quadrumana, — is no more to be regarded as iden- 

 tical with the placoids, than the red-blooded animals are to 

 be regarded as identical with the apes or with the human fa- 

 mily. It simply includes them in the character of one of the 

 three great divisions into which it has been separated, — the 

 division ranged, if I may so express myself, on the extreme 

 right of the line ; its middle portion, or main body, being 

 composed of the SturioneSy — a family on the general level of 

 the osseous fishes ; while, ranged on the extreme left, we find 

 the low division of the Suctorii, i. e. Cyclostomi, or lam- 

 preys. But with the middle and lower divisions we have 

 at present nothing to do ; for of neither of them, whether 

 Sturiones or Suctorii, does the Silurian system exhibit a 

 trace. Further be it remarked, that the scheme of classi- 

 fication which gives an abstract standing to the Chondrop- 

 terygii is in itself merely a certain perception of resemblance 

 which existed in certain minds, having cartilage for its gene- 

 ral idea ; just as another certain perception of resemblance 

 in one other certain mind had cuticular skeleton for its ge- 

 neral idea, and as yet another perception of resemblance in 

 yet other certain minds had red blood for its general idea. 

 As shown by the disparities which obtain among the sec- 

 tion which the scheme serves to separate from the others, it 

 no more determines rank or standing than that greatly more 

 ancient scheme of classification into " ring-streaked and 

 spotted," which served to distinguish the flocks of the pa- 

 triarch Jacob from those of Laban his father-in-law, but 



