10 AKT. 20. — M. YOKOYAMA. 



Edw. (Eocene Mollusca, Bivalves, p. 148, pi. XXII, iig. 13) 

 from the London Basin, in which, however, the ribs number 

 about 30. 



Found at depths of 405 ft. and 609 ft. 



8. Venus Mitsuiana u. sp. 



PL I. Figs. 5a, 5b. 



The shell is small, convex, subtrigonal, very inequilateral 

 with the anterior side only about one-third as long as the 

 posterior. The anterior border of the shell is sloping and 

 nearly straight, making a rounded angle with the broadly 

 arcuate ventral border ; the postero-ventral corner is rounded 

 and less sharp than the a ntero- ventral. The surface is smooth, 

 furnished only with lines of growth. The beaks are small and 

 touch. Length 18 millim.; height 13 millim.; thickness 8 millira 



There is only a single specimen of this species the shell of 

 which seems to have been rather thin. 



As it is impossible to expose the hinge, the generic deter- 

 mination must be taken as provisorial. 



Taken from a depth of 277 feet. 



9. Fusus sp. 



PI. II. Fio;. 7. 



'&• 



A medium-sized form having a long canal with the spire 

 broken off. The body whorl shows two sharp spiral ridges one 

 corresponding in position to its shoulder-part and the other 

 separating the lateral surface from the lower. The interspace 



