ON CILIARY MECHANISMS. 



289 



from the body is such that the plane of the first and longest turn of the 

 lophophore on each side subtends the antero-lateral angle of the shell. 





Fig. 5. — View of a portion of the lopliojjhore, including the buccal groove and th& 

 base of five gill-filaments of Crania. Three of the filaments are ventral and two 

 dorsal ones. 



(For the sake of convenience the lophophore is magnified less than the gill- 

 filament?. Drawn from the living object.) 



The dotted arrows indicate the direction in which the cilia on the body of the 

 lophophore lash, the arrows on the filaments the direction in which the food- 

 collecting, the frontal cilia lash, and the thin-lined arrows below the buccal lip 

 the direction in which the ciha lash in the buccal groove. 



A. Ridge on the lophophore away from which the cilia on both sides lash. 



B. Arrows indicating the direction in which the lateral, i.e. current-producing. 



cilia, lash. 

 B.l. Buccal lip overlying buccal groove. 



B.gr. Buccal groove along which are carried the particles from the lophophore. 

 I.e. Lateral cilia. 

 f.c. Frontal ciha. 

 v.f. Filament of ventral series. 

 a.f. (d.f.) Filament of dorsal series. 



Consequentlv the main current is drawn into the shell at the antero- 

 lateral angles, since the lateral cilia lash on the whole in a direction at. 

 right angles to the plane of the lophophore. 



