770 



Mag. de Zool. pi. 20. P. Californica, Conrad. P. arcuata, Besh. 

 Guer. Mag. Zool. pi. 19. P. subglobosa^ Sowerhj, Genera, f. 6. 



"Pet. testa ovato-transversa, insequilaterali, globoso-cylindracea, 

 aliquando abrupte truncata, rufo-grisea, transversim irregulariter 

 striata, intus albu ; eardine bidentato, iu altera valva unidentato ; 

 dentibus obliquis." 



This shell is surely much more allied to Venenipis than to 

 Petricola ; it has only transverse sculpture ; it is very irregular, 

 and sometimes very much attenuated at the hinder end. 



California. 



SPECIES NOT IDENTIPIED. 



V. nucleus, Lamk., Anim. s. vert. 

 V, distans, Lamk., Anim. s. vert. 



LIST OF FIGURES IN PLATES CLXIV. AND CLXV. 



{The Figure after the Name refers to the number of the Species.) 



