2^0 POLORTHUS. 



P. BiLOBATUM, Desl. PL 104, figs. 580, 581. Upper Lias of 

 Normandy. 



Genus POLOETHUS, (!abb. 



The aggregated mass of specimens forming the type of this 

 genus was originally referred to Teredo ; subsequently, in des- 

 cribing the genus, Mr. Gabb referred it to Yermetidte, and in 

 1872 he finally believed it to be a cephalopod connecting the 

 Orthoceratidse with Beatrice^e. The aggregate character, the 

 long, narrow, irregular tube, the non-molluscan character of 

 the partitions forbid this determination : I am convinced that 

 Polorthus is not a mollusk, and Beatricea itself is now referred 

 doubtfully to the SpongiadiP. 



