FOSSILS OF OLD RED SANDSTONE. 53 



animals in general.* The maxillary and inter- 

 maxillary bones are in them rudimental. Their 

 tails are finned on the under side only, an admitted 

 feature of the salmon in an embryotic stage ; and 

 tlie mouth is placed on the under side of the head, 

 also a mean and embryotic feature of structure. 

 These characters are essential and important, 

 whatever the Edinburgh reviewer may say to 

 the contrary ; they are the characters, which, 

 above all, I am chiefly concerned in looking to, for 

 they are featiu-es of embryotic progress, and em- 

 bryotic progress is the grand key to the theory of 

 development. I therefore throw back to my re- 

 viewer the charge that I have " clung to feeble 

 analogies," and " kept out of view the broad and 

 speaking facts of nature." 



With regard to the alleged falsity of the crus- 

 tacean character of some of these fishes, and the 

 discredit of repeating the blunders and guesses 

 made by the first observers, before any good 

 evidence was before them, I can only say, that 

 at the time when my book was written, geologists 

 and inquirers into fossil ichthyology of the highest 



* Cartilage, " in many animals, forms the entire stractare, and 

 in the early state of the human embryo it does the same." — 

 Carpenter's General Physiology, p. 37. 



