480 FOSSIL INVERTEBRATED ANIMALS. 



having lived in the ancient sea ; because^ hitherto, no hving 

 analogues have been recognized of them, and they are only 

 found in mountains of tolerably ancient formation. They are 

 to be seen of a monstrous bulk, nearly six feet in diameter : 

 sometimes they are accumulated to such a degree as to form 

 entire rocks. The oryctologists have engraved many species, 

 but their works are, in general, so little methodical, that great 

 difficulty is experienced in studying them. Fossil ammonites are 

 sometimes to be met with, under their testaceous form^ without 

 any stony concretion in their interior. Their structure is then 

 very visible; and it was on species of this kind that Bruguieres 

 established the genus, which^ before his time^ had been but 

 simply indicated. 



Lamarck has separated from the ammonites the species 

 which were not articulated, to form a new genus^ under the 

 name of Planulites. 



The ammonites have at all times formed a very striking ob- 

 ject of human contemplation, whether we consider their bulk, 

 their abundance, or the places in which they have been found. 

 In India they constitute, or rather their moulds, an object of 

 veneration to the people, under the name of Salagraman, 

 because it is believed that one of their gods is concealed therein. 



Bruguieres, in the Encyclopedie M^thodique, mentions twen- 

 ty-two species of ammonites, most part of which have been 

 figured by Bourguet and Langius ; but this number might 

 easily be tripled with the species found in France alone. The 

 chain of secondary mountains^ which extend from Langres as 

 far as the environs of Autun, that one near which the town of 

 Caen is built, and many others, contain such immense quan- 

 tities, that the roads are paved with them. It is usually in very 

 argillaceous schists, in very calcareous and ferruginous ar- 

 gillse, and in the lower chalk, that they are to be met. They 

 are also found frequently in calcareous rocks, and are often 

 adherent thereon by one of their sides ; a fact which is not 

 explained in a very satisfactory manner. Some of them are 



