FEEDING OF CREPIDULA. 



457 



(7 and 9) has treated other forms in more detail ; and about the same 

 time Herdman and Hornell (10) described the mode of feeding in the 

 Ceylon pearl oyster. 



The following description of the mode of feeding in the European 

 oyster contains little that has not already been noted by these writers 

 in similar forms. The native oyster {Ostrca ednlis) draws a food- 

 current into the mantle cavity between the mantle lobes antero- 

 ventrally. The current does not enter along the whole of the ventral 

 surface, however, w^hen the animal is feeding normally, but only in 

 a small restricted part such as is indicated in Fig. 10. It is only in 

 this part that the ventral edges of the mantle lobes are not apposed, 

 and the opening thus produced forms practically an inhalent aperture. 

 The outgoing current leaves the mantle cavity postero-dorsally (see 



CUT-GO/NG 



Fig. 10. — View of mantle cavity of the native Oyster {Ostrea eduUs) from the right side 

 to show the food currents. (Drawn from life, natural size. ) 

 The ingoing current enters the mantle c*\'ity between the points E and F. 

 The dotted arrows indicate the directions in which the mantle cilia lash. 

 The arrows on and at the edges of the gill-lamellae indicate the paths of the main food- 

 streams. 



A. Point at which the heavier particles begin to fall out of the main food-stream. 



B. Minor food-stream at the base of a gill-lamella. 



C and D. The ciliated path on the mantle which carries away food-material rejected by 



the palps and the particles collected from the mantle. 

 E and F. Region in which the oyster commonly takes in its main food-stream. 



>"EW SERIES. — VOL. IX. NO. 3. Jt.">"E, 1912. 2 G 



