134 



THE LIASSIC PERIODS. 



CHAP. 



Marlstonef . 



*A. spinatus. 



*A. margaritatu 



DISTRIBUTION OF SOME FORMS OF LIASSIC LIFE. 



*Belemnites irregularis. 

 Belemnites Voltzii. 



*Belemnites eloiigatus. 

 *Pecten sequivalvis. 

 *Belemnites paxillosus. 

 *Cardium truncatum. 



*Hippopodium ponderosum. 

 *Cardinia Listeri. 



*Belemnites acutus. 

 *Lima gigantea. 



Ichthyosaurus intermedius. 



Plesiosaurus megacephalus. 

 *0strea liassica. 

 *Avicula contorta. 



*A. planorbis. 



'Rhseticbeds 



FOSSILS OF THE LIASSIC PERIOD. 



PISCES. 



Acrodus minimus. R. Westbury. 



Aechmodus angulifer. L. Near Strat- 

 ford. 



Aechmodus dorsalis. L. Byrford, Glou- 

 cestershire. 



Ceratodus altus. R. 



Dapedius orbis. L. Bidford. 



Gyrolepis Alberti. R. Wickwar. 



tenuistriatus. R. Westbury. 



Hybodus minor. R. Westbury. 



Leptolepisconcentricus. U. Dumbleton. 



Nemacanthus filifer. R. Westbury. 



monilifer. R. Aust, West- 



bury, &c. 



Pachycormus latirostris (?). U. Glou- 

 cestershire. 



Pholidophorus crenulatus. U. Dumble- 

 ton. 



Pholidophorus Stricklandi. L. Bidford. 



Saurichthys apicalis. R. Westbury. 



Tetragonolepis discus. U. Dumbleton. 



Of the fishes here mentioned some are Placoid, and allied to 

 sharks. Such are Acrodus and Ceratodus, known only by teeth; 



* The fossils marked thus are figured in Plates VII. and VIII. 



f In the district around Oxford it is not satisfactory to mark off, as belonging to 

 the middle lias, any of the argillaceous beds below the marlstone. In Yorkshire and 

 on the Dorsetshire coast the case is somewhat different. These beds below the principal 

 mass of marlstone include Ammonites capricornus, Jamesoni, fimbriatus, Henleyi. 



