236 FOSSIL REPTILES. 



bank of blue marly stone, analogous to our lias, which rests on 

 the red sand-stone. Mr. de Lab^che believes that this lias of 

 France contains bones of the ichthyosaurus, as well as that of 

 England. From the ascertainment of these three distinct 

 banks of blue marie, there must be a considerable difference 

 between the ages of the crocodiles there found. 



The view we have just given is taken from Mr. de Labeche. 

 M. Prevost, who has very accurately examined the coasts from 

 Calais to Cherbourg, agrees with him to a certain point. Ac- 

 cording to him, the upper strata are the bluish argilla of the 

 environs of Havre, with lignites. Then comes the limestone of 

 Caen, the upper strata of which contain polypiers, trigoniae, 

 and cerithia^ and the lower contain bones of crocodile. Under 

 this hmestone come the lower blue argilla, and the oolites, 

 alternating with the lias, containing, or supposed to contain, 

 the ichthyosaurus, and all would rest on the limestone with 

 gryphytes, and the limestone used for lithographic operations. 



Be all this as it may, it is incontestable that the crocodile of 

 Caen, like the last described, and those of Honfleur, and many 

 others, belongs to this great assemblage of strata, which con- 

 tinental geologists have agreed to call the formation of Jurat 

 and which holds a sort of middle rank among the secondary 

 strata, being placed below the chalk and above the other 

 secondary formation, which has been named Alpine. 



This crocodile of Caen does not appear to have been very 

 rare in these environs at the epoch in which it lived ; for, within 

 but a few years, comparatively speaking, have been found the 

 remains of at least ten individuals. The specimen which has 

 excited most attention was found at the end of 1817, in part 

 of the banks of Caen-stone, on the right of the Orne, and in 

 the quarries of a village called Allemagne, a short league to the 

 south of Caen. 



The principal piece was composed of from fifteen to sixteen 

 vertebrae, placed on a continuous hne, and pretty nearly in 



