668 JAMES L. KELLOGG 
groove on both lamellae, then forward, to be transferred to palp 
surfaces. 
Palps. The organs are large and the ciliation of margins and 
folds, as indicated in the drawing, is of the usual character. It 
was in the Atlantic Cardium mortonii that the cilia tracts in the 
grooves between folds were first seen. There, and in C. corbis, 
the folds lift to expose the grooves when much material is present 
on the palps, and this, being swiftly drawn into them, is carried 
to the outgoing tract of the ventral margin. Attention shouldbe 
called to the fact that the lateral part of the oral groove (lq), 
shown in this and many other figures, may experimentally be 
filled to overflowing with material, since currents are directed 
into it from above and from the sides. All this material will be 
moved downward, but, on reaching a point indicated by the line 
from reference letters lg, it encounters a powerful ciliation on the 
groove walls directed outward to the ventral palp margin. This 
outgoing ciliation extends so far into the groove at this point 
that only small quantities of material can continue in it toward 
the mouth. It is the very narrow gateway into the last and 
narrowest path to the mouth, the proximal oral groove, and is 
present in all cases in which the oral groove is extended upward 
on the sides of the body between the fused pslps. Unless the 
sand eating Macomas, in which the mouth region was not care- 
fully studied, are excepted, apparently in all cases only a very 
narrow and attenuated stream of material can enter the mouth. 
Visceral mass. The ciliation is to the posterior wall, from 
which material falls to the mantle. 
Mantle. Mantle collections are moved to a line parallel with 
its edge, then backward near the base of the incurrent siphon, 
where, over a small area, they are forced between the mantle 
edges to the exterior, instead of being collected and expelled 
periodically through the siphon. This is the usual procedure in 
forms with free mantle margins, and which are not completely 
buried in a burrow. 
