6 JURASSIC FAUNA. 



Locality and stra tig raphical position. — Maz^r Drik, Polyphemus-limeBtone. 



Remarks. — Although fairly common, none of the specimens are well enough 

 preserved to permit of a specific determination. To judge from its general feature, 

 this species seems to be closely related to Flagiostoma semi-circulare, Goldf., from 

 which, however, it is apparently distinguished by much coarser ribs. 



Sub-order: MYTILACEA. 

 Family: AVICVLIDM 



Genus : GERVILLIA, Defr. 



Gervillia sp. 



A few fragments of an elongated shell probably belong to this genus. But 

 they are too badly preserved to allow of further determination. The left valve is 

 transversely elongated and slightly inflated, the right valve is flat and somewhat 

 concave towards the dorsal margin. If any conclusion can be drawn from such frag- 

 ments it may be said that in general shape this species seems to be related to Gervil- 

 lia aviculoides,Bow. 



Locality and stratigraphical position. — Mazd^r Drik, Polyphemm-\iva.estoTXQ. 



2. Order: I>ESMODONTA. 

 Family: PHOLABOMTIBM, Desh. 



Genus: PHOLADOMYA, Sow. 



Pholadomya sp. Plate I, fig. 7. 



This genus is represented by a very much deformed specimen of apparently 

 rectangular shape. Anterior portion very short, posterior side elongated. Beaks 

 low, depressed, very near the anterior margin. Surface covered with 13 radiating 

 fine ribs, which are apparently closer together on the anterior than on the posterior 

 side. 



Locality and stratigraphical position.— MdiZir Drik, PoZyjjAemtts-limestone. 



2. Class: GASTROPODA. 



Order: FBOSOBBANGEIATA, Cuv. 



Sub-order : ASPIDOBRANCHIATA. 



Family : PLEUROTOMARIID^. 



Pleurotomabia sp. 



The only representative of the gastropods which has been found, is the cast of 

 a tolerably large trochiform shell, which probably belongs to this'genus. It consists 



