270 I'nl.ORTHUS. 



P. BILOBATUM, Desl. PI. 104, figs. 580, 581. Upper Lias of 

 Normandy. 



Gteinu POLORTHUS, (Jabb. 



Tin- riii-givgatcd ma>s of >pccimciis forming tlie type of this 

 genus was originally referred to Teredo; subsequently, in 'It-s- 

 cribing tlir uvims. Mr. <ial>l> referred it to Yermet i<la-. an<l in 

 1872 he finally believed it to be a cephalopod connecting the 

 Orthoceratidjv with licat rie-ca-. The ai^Tegate character, the 

 long, narrow, irregular tnl>e, the non-molluscan eha racier of 

 the partitions forbid this determination : I am convinced that 

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

 doubtfully to the Spongiada-. 



