Ch. XXI.] 



FOSSILS OF THE LIAS. 



421 



them is a species of Lepidotus (L. gigas, Agass.), fig. 451, which is 

 found in the lias of England, France, and Germany.* This genus 

 was before mentioned (p. 349) as occurring in the Wealden, and is 

 supposed to have frequented both rivers and coasts. Another genus 

 of Ganoids (or fish with hard, shining, and enamelled scales), called 

 Mchmodus (see fig. 452), is almost exclusively Liassic. The teeth 



Kg. 452. 



K 



6. Scales of JEctimodus 

 Leachii, 



a. JEchmodus. Kestored outline. 



c. Scales of Dapediw 

 mowilif&r. 



of a species of Acrodus, also, are very abundant in the lias (fig. 

 453). 



Kg. 453. 



Acrodus noMlis, Agass. (tooth) ; commonly called " fossil leech. 

 Lias, Lyme Eegis and Germany. 



But the remains of fish which have excited more attention than 

 any others are those large bony spines called ichthyodorulites (a, fig. 



Kg. 454. 



Hybodu% reticulatus, Agass. Lias, Lyme Eegis. 

 a. Part of fin, commonly called Ichthyodorulite. &. Tooth. 



454), which were once supposed by some naturalists to be jaws, and 

 by others weapons, resembling those of the living Balistes and Silu- 



* Agassiz, Poissons Fossiles, vol. ii. tab. 28, 29. 



