674 JAMES L. KELLOGG 
surfaces of large, or chemically irritating collections. It is an 
important function, and many observations have been made on 
it during the progress of this study; but it may only be stated 
that much material causes the gill grooves of Pecten to open wide, 
gga ie, 
Wa Il \ 
\ \ { attic 
We See 
ee 
Se ia esa 
Ng ON. 
i. va = 
RSS Ae 
i ee 
Ss ten 
—s 
=== A eae i 
= \ 
se ‘ S ie 
—p \ r 1 “ 
== iN . Nt le 
Be Se i ae 
aa eee 
ee Sk OND ee eran 
ee NS SO ee 
i ras \Ny, 
LN) ae ie 
46 
Fig. 46 Pecten tenuicostatus; mantle ciliation; a, adductor muscle; 2, 
vortices; between x and y material is moved to the surface of the adductor muscle. 
Fig. 47 Pecten irradians; mantle ciliation; letters as in figure 46. 
and then to close with so sudden a contraction that material 
is thrown out of them. Often this violent bending of filaments, 
which results in spreading open and then constricting the grooves, 
