EEYNELL : ON CASSIDARIA RVGOSA. 



293 



form of a straight tube about 8 mm. long. The whole of the foot, 

 perhaps through contraction caused by the preserving fluid, is 

 tuberculately reticulated and the margin crenulated. Kiener shows 

 the foot with a broad untesselated margin, but I could trace no 

 suggestion of this. 



Operculum. Distinctly oval, and in texture and colour horny, 

 semitransparent, subconcentrically striate, with the nucleus nearly 

 marginal. It measures 32 by 14 mm. 



Tentacles (Figs. 1,2, 3, L.T., R.T.) two in number, long and fairly 

 thick, decreasing rapidly in size towards their free ends, but some- 

 what bluntly pointed. Corrugated and transversely striated through 

 contraction. 



/^/y £ ^'<>-3 



F,g.4- 



Eyes (Figs. 1, 2, 3, R.E., L.E.) two in number, placed on tubercles 

 at the base and on the outside of the tentacles. They are pigmented 

 with black, as are, to some extent, the tubercles. 



The rhynchostome (Fig. 2, Rh.) is a plain, simple, rounded opening. 



The tntrovert (Fig. 2, Inv.) is comparatively short, and conical in 

 shape, with a bulbous swelling at the fi'ee end, flattened dorso- 

 ventrally, transversely striate, thick-walled and muscular, especially 

 towards the posterior, where it is attached by two more or less 

 distinct bands of muscles (the introvert retractors, Fig. 1, R.M.) 

 to the underside of the floor of the pallial chamber. It is pigmented 

 with purple towards the free end, deepening in colour as the mouth is 

 reached. 



VOL. VI. — JLXE, 1905. 



21 



