FEEDING OF CREPIDULA. 



461 



touch the mantle during feeding, and in this way form at this point a 

 temporary food-groove. Otherwise the food-streams in these forms 

 are similar to those of the oyster. In Cardium the frontal cilia on the 

 outer gill-lamellae lash towards the edge of the gill on the outer faces 



/f^GO/NG 



OUr-GO/A/G 

 CUff/iENT 



//VGO/AfG 

 CU/fRENT 



*FiG. 13. — View of mantle cavity of tlie scallop, Peden maximus, to show the food-streams, 

 seen from tlie left side with the mantle supposed to be cut away. (Drawn from 

 life, natural size. ) The posterior ends of the gills are somewhat retracted. In 

 feeding, these spread across to the edge of the mantle and divide the cavity into 

 inhalent and exhalent chambers. 



The dotted arrows indicate the directions in which the mantle cilia lash, and the 

 dotted line on the ventral part of the mantle between A and B indicates the ciliated 

 path. 



The small arrows at the edges of the gill-lamellae and of the reflected filaments 

 indicate the imths of the main food-streams which lead to M, the region of the 

 mouth. The arrows at the proximal ends of the gills, as at E C, indicate the 

 direction of the exhalent current. 



A. Point at which tlie heavier particles settle out of the main fooii-streams. 



B.C. The ciliated path on the mantle. 



E.G. Exhalent currents. 



F. Foot. 



M. Region of mouth. 



P. Left outer palp. 



R. Rectum. 



* I am indebted to Mrs. Orton for this drawing, for assistance in the drawing of the 

 oyster (Fig. 10) and also Fig. 14, 



