ON CILIARY MECHANISMS. 



303 



THE ENDOSTYLE OF CREPIDULA AND CALYPTR.EA. 



At the base of the gill-filaments of Crepidula and Calyptrsea there is 

 a group — or rather there are two groups — of large glandular ciliated cells 

 which secrete a mucoid substance (see Figs. 10 and 12, p. 304). Examination 



Tig. 11. — View of the endostyle and the ba.ses of four gill-filaments of Crepidula fornicata 

 highly magnified. (Drawn from the living object.) 



The dotted arrows on the endostyle, EN, and the complete ones on the bases 

 of the gill-filaments indicate the direction in which mucus is passed from the 

 endostyle on to the bases of the gills. The dotted arrows on the mantle on the 

 floor of the inhalent chamber, m, show the direction in which the ciUa in this 

 region lash. Similarly the forward stream in the ciliated groove, c.gr., on the left 

 of the endostyle is indicated by the overlying dotted arrows. 

 EN. The endostyle consisting of two rows of gland cells between and to the left 



of which are rows of specially differentiated ciliated cells, 

 c.gr. Ciliated groove on the left of the endostyle. 

 g.f. The bases of the gill-filaments. 

 f.c. Frontal cilia of gill-filaments, 

 m. The mantle covering the floor of the inhalent chamber. 



of the living gill and the surrounding parts shows that the cilia of these 

 glandular cells lash the secreted mucus on to the bases of the gill-filaments, 

 whence it is passed along the face of the gill to be used for the purpose of 

 entrapping food-particles (see Figs. 10 and 11, above), as has already been 



