FEEDING OF CREPIDULA. 



459 



same way as the " curtain " in Mytiliis. In Pecten water is drawn into 

 the mantle cavity along the whole of the ventral and part of the 

 anterior surface, but chiefly in two restricted areas. One of these areas 

 is indicated by the large arrow pointing to B in Fig. 13, and the other 

 is shown approximately by the large arrow passing near A, Fig. 13. 

 The ciliated path on the mantle in Pecten collects particles from the 

 whole of the ventral region of the mantle (see the dotted line C A B in 

 Fig. 13) and washes them anteriorly to the edge of the mantle (see 

 Fig. 13, B), whence they are expelled along with the material rejected 

 by the palps. 



While the heavier particles are dropped out of the current just 

 inside the mantle cavity in the oyster, the finer particles travel onwards 

 in the stream until they reach the gill, which retains them while 

 allowing the current to pass onwards into the exhalent chamber. The 

 food-particles drawn against the gill-filaments are caught in the mucus 

 secreted by the gill and washed to the distal edges of the gill-lamellae, 

 where they are formed into a cylindrical mass. This mass is then pro- 



FiG. 11. — View of the mantle cavity of the common mussel, Mytilus edulis, from the left 

 side to show the food-currents. (Drawn from life, about natural size.) The 

 arrows on and at the edge of the gill-lamellae (G) indicate the paths of the main 

 food-streams. 



C.P. The dotted arrows and line at the ventral edge of the mantle indicate the ciliated 

 path which carries the material rejected by the palps and that collected from 

 the mantle to the point indicated by the arrow above B in the figure. Here the 

 rejected material is pushed into the exhalent current. 



A. Arrows indicating the paths of the heavier particles settling out of the main food- 



stream. 



B. A sort of curtain hanging from the dorsal part of the inhalent aperture. 



C. The line of attachment of the mantle to the body-wall. 



D. Arrows in the supra-branchial chamber indicating the direction of the exhalent 



current. 



E. Uplifted left border of the inhalent aperture to show the curtain, B. 



F.H. Points between which the main food-current is drawn into the mantle cavity. 



G. Left outer gill-lamella. 



P.P. Left palps between which the edges of the left gill-lamellae may be seen to end. 



PiP' Right palps. 



M. Locus of the mouth. 



