PART II. CHAPTER 



Fossils of the Lias. 



white colour, and have been called white lias. In some parts 

 of France, near the Vosges mountains, and in Luxembourg, M. 

 E. de Beaumont has shown that the lias containing Gryph&a 

 arcuata, Plagiostoma giganteum, and other characteristic 

 fossils, becomes arenaceous ; and around the Hartz, in West- 

 phalia and Bavaria, the inferior parts of the lias are sandy, and 

 sometimes afford a building stone called by the Germans qua- 

 dersandstein. 



The name of Gryphite limestone has sometimes been applied 

 to the lias, in consequence of the great number of shells which 

 it contains of a species of oyster, or Gryphsea (Fig. 221.). 

 Many cephalopoda, also, such as Ammonite, Belemnite, and 

 Nautilus (Fig. 222.), prove the marine origin of the formation. 



Fig. 221. 



Fig. 222. 



Oryphcea incurva, Sow. 

 (G.arcuata, Lam.) 



Nautilus truncatus, Lias. 



The fossil fish resemble generically those of the oolite, belong- 

 ing all, according to M. Agassiz, to extinct genera, and differing 

 remarkably from the ichthyolites of the cretaceous period. 

 Among them is a species of Lepidotus (L. gigas, Ag.) Fig. 

 202.), which is found in the lias of England, France, and Ger- 



a Fig. 223. 



Scales of Lepidotus gigas, Agas. 

 a. two of the scales detached. 



many.* This genus was before mentioned (p. 348.) -as occur- 

 ing in the Wealden, and is supposed to have frequented both 



* Agassiz, Pois. Fos. vol. ii. tab. 28, 29. 



