Recherches sur les Poissons Fossiles. 



67 



It is in the series of deposits inferior to the has that we 

 begin to find the largest of those monstrous Sauroid fishes, 

 whose osteology resembles so much the skeletons of the 

 Saurians, whether by the more intimate sutures of the bones 

 of their cranium, or by their large longitudinally striated 

 and conical teeth, or by the manner in which the spinous 

 apophyses are articulated with the body of the vertebrae, and 

 the sides to the extremity of the transverse apophyses. 



The analogy which we find between these fishes and the 

 Saurians, is not merely confined to the skeletons in one or 

 two genera, which still maintain their existence. I have 

 found a very peculiar internal organization of their soft 

 parts, which approaches still more to the group of reptiles, 

 as will appear presently. There is in fact in the Lepidosteus 

 osseus, a glottis, the same as in the Sirens and Salamandrous 

 reptiles, a cellular air, or swimming vessel, with a trachea 

 or wind-pipe, as the lungs of an Ophidian, In short, their 

 covering appears to resemble that of the crocodiles, from 

 which they are not always to be easily distinguished. 



The small number of fishes found in the transition beds, 

 do not allow us yet to assign a particular character to them. 

 However, the species in the collection of Mr. Murchison, 

 already shew, that their types do not extend to the coal 

 formation. 



What is most remarkable in all the fishes below the 

 oolitic series, (except their analogy with the reptiles,) is the 

 great uniformity of types on the one hand, and on the other, 

 the great uniformity of the diflTerent parts of the same animal 

 among themselves, which are consequently difficult to distin- 

 guish, such as the scales, the bones, and teeth. If it were al- 

 lowable here to hazard a conjecture on such a state of things 

 from what is now presented to usj there would appear to 

 be some reason to think, that the principle of animal life 

 was slowly developed under the form of ordinary fishes ; and 

 that reptiles, birds, and mammalia, gradually advanced, or 



