666 JAMES L. KELLOGG 
amount, it then proceeds along the extensive proximal oral groove 
and into the mouth. Below the line x, material is carried to the 
demibranch margin, and then posteriorly in its groove (fig. 34) 
to be cast off on to the mantle. This is the only species examined 
(except Yoldia limatula and Pecten, which possess mechanisms 
quite different) in which any part of the gill collections is carried 
away from the palps on outgoing tracts. Apparently the narrow 
strips at the bases of the lamellae collect sufficient food; but even 
their collections may be lost before reaching the palps, for if a 
large quantity of material is placed on them, some of it is apt 
to touch the suspending membrane (gm), in which case all will 
be pulled on to it and carried backward over the white folds of 
the mantle. In no other case has a more furious ciliary action 
been observed than on the gills and mantle of this form. 
The anterior end of the gill of the right side is shown at gr. 
From this end, the gill bends downward, slightly forward, and 
then posteriorly in a curve parallel with that of the left side. It 
is suspended from the mantle, and its ciliation is like that of the 
left side. 
Palps. The entire extent of these organs is shown in figure 34, 
and their chief cilia tracts are those of other bivalves, as indi- 
cated. Time was lacking to determine the presence or absence 
of the fine dorsally and ventrally directed tracts on the folds. ° 
Visceral mass. The ciliation of the extensive visceral mass is 
indicated in figure 34, and requires no comment. 
Mantle. All material collected or transported by the mantle is 
brought to a point, b, on the posterior edge, being held in place 
by the free fold until a large ball is formed. This is thrown out 
by a sudden contraction of the adductor which closes the valves. 
A very active special groove of the mantle parallels the oral 
groove anteriorly and dorsally. It is an outgoing tract, directing 
its stream posteriorly. 
Tagelus californianus Conrad 
The specimen examined was from San Diego Bay. Figures 
36 and 37 show the ciliation to be the usual one in most respects. 
Currents on all gill faces are to the margins and forward. On 
