Fossil Fishes. 



43 



" It is in the series of deposits inferior to the Lias that we begin to 

 discover the largest of those monstrous Sauroid fishes, whose osteol- 

 ogy approximates them so much to the skeletons of the Saurians, by 

 the stronger sutures of the cranial bones, by their great conical teeth 

 with longitudinal striae, and also by the mode in which the spinous 

 apophyses are articulated with the bodies of the vertebrae, and the ribs 

 also at the extremity of the transverse apophyses. The analogy be- 

 tween these fish and the Saurians goes further than the skeleton : in 

 one of the two species which is now alive, I have found an interior 

 organization of soft parts, which is very peculiar, and which approx- 

 imates these groups of animals more than at first was anticipated. 

 In the Lepidosteus osseus there is a real glottis, like that of the si- 

 rens and the salamander reptiles, also a cellular swimming bladder, 

 with a trachea, as in the lungs of an ophidian. Finally, these in- 

 teguments have often an appearance so like to those of the crocodile, 

 that it is not always easy to distinguish them. 



" The sm&ll number of fishes found in the transition rocks appear 

 not as yet to enable us to assign to them any peculiar character. At 

 the same time, the species in the collection of Mr. Murchison ex- 

 bibit types which are not found even in the coal measures. 



" What is very remarkable in all the fishes below the oolite spe- 

 cies, besides their resemblance to reptiles, is, on the one hand, the 

 greatest uniformity of their types ; and on the other, the very great 

 uniformity of the parts of the same animal among themselves; so 

 much so, that the scales, the bones, and the teeth of one are with 

 difficulty distinguished from those of the other. And if we might 

 here hazard a conjecture on this state of matters, we should be nat- 

 urally led to fancy that the principle of animal life, which developes 

 itself at a later period under the form of our common fishes, of rep- 

 tiles, birds, and beasts, is at first, entirely confined to these singular 

 sauroid fishes, at the same moment participating of the nature of fish- 

 es and of reptiles ; and that this mixed character is only lost in this 

 class upon the appearance of a greater number of reptiles, as we 

 see the Ichthyosaurus and Plesiosaurus participate, as to their bony 

 structure, in the characters of the cetaceae, of the class of mammife- 

 ra ; and the great terrestrial saurians to those of the Pachydermae, 

 which would appear to have been called into existence at a much 

 later period. 



" We are thus by observation conducted to those ideas of the phi- - 

 losopby of nature which are presented to us by an organic and reg- 



