74 



Recherche s sur les Poissons Fossiles. 



M. Bronn first pointed the distinction between the spe- 

 cies described by Mr. De la Beche ; some having crenated 

 sloping teeth, and some pointed teeth: to the latter he 

 gave the name of Tetragonolepis, and these distinctions 

 have been adopted by M. Agassiz. Dapedius Colei, at first 

 view would appear to an uninitiated observer as something- 

 like the Bream; but on closer inspection, the scales are 

 seen to be square, as represented on the following page, 

 and are covered by a coat of enamel — peculiarities which 

 alone distinguish these fossils from all existing fishes. " The 

 osteology," says M. Agassiz, " of the genus Dapedius is 

 most interesting. In a specimen figured by Lord Cole on 

 a fly leaf, and from which I have taken a drawing, we see a 

 great part of the skeleton, the examination of which has en- 

 abled me to clear up many questions connected with the 

 anatomy of the family. The bodies of the vertebrae are 

 wanting, as in all the Lepedoides of whose skeletons I have 

 seen any portion, but the sides and all the superior spi- 

 nous apophyses are very well preserved. The sides are 

 dilated and flat at their insertion; the rest, granular and 

 round, are not expanded downward more than half the 

 height of the abdominal cavity. The superior spinous apo- 

 physes are composed of many pieces, as in the Caturus ; and 

 have the base united to the body of the vertebrae by two 

 little short pieces, which are surmounted again by other 

 more elongated pieces," &c. Then follows a minute de- 

 scription of the various processes of the vertebrae, and their 

 relations with the bones supporting the fins, all which are 

 represented in drawings. Of the head we distinguish the 

 operculem, the sub-operculum, and pre-operculum, or gill 

 covers. The thoracic, the temporal, the jugular bones, and 

 the jaws with their numerous ranges of furrowed teeth, (dents 

 echancrees the pterygoid with the teeth in groups on the 

 surface, and the palatine with some bifurcated teeth — the 

 interior surface of the frontal bone, are all minutely described 



