696 JAMES *L. KELUOGG 
activity of the gill in collecting and moving forward suspended 
particles brought to it in the water, could have escaped his notice, 
the whole process being precisely like the food collection of other 
lamellibranch gills. The pumping action of the gills does not 
disturb small collections, and there is no reason for assuming 
that it would interfere with the transfer of food from gill to palp. 
Collections of the palp appendage. In the quotation above, 
Drew refers to his own observation of collections made by the 
palp appendages, which I have confirmed many times. ‘This 
structure (fig. 70, pa) is a trough, the convex surface normally 
opening ventralward when it is extended from the body, and 
allowed to rest on the surface of the mud. Here, as Drew de- 
scribes it, great quantities of material, “foraminifers, ostrocods, 
and even small lamellibranchs and gastropods, together with the 
smaller forms and mud, are passed along the groove, finally 
between the palps, and so on into the mouth.”’ 
The relation of this groove of the appendages to other ciliated 
tracts—the oral, and several outgoing streams—is shown at the 
point x in figure 70. The letter is placed close to a narrow notch, 
bounded on either side by the outgoing tracts of the dorsal 
margins (dm). The only passage to the mouth from this entire 
region is through the notch (indicated by the bent arrow) and 
when in scores of trials the dorsal tracts were spread apart as 
far as possible, no large amount of material was ever allowed to 
pass through it but was always seized by these outgoing tracts. 
Always, when large quantities of material were brought to this 
gateway, along the groove of the appendage, as well as along the 
lateral oral groove, they were halted and turned on to outgoing 
tracts, especially those of the dorsal margins (dm). The dorsal 
margin of the posterior palp is very wide, and is bent into a 
broad, shallow trough which is continuous with the groove (Ig) 
above it. From the notch « there are also outgoing tracts on 
the sides of the groove of the appendage, as shown in figures 70 
and 71, which carry away a small amount of material. Very 
narrow streams of material, on the other hand, were able to enter 
between the inner palp faces, and were often found collected 
there in considerable quantity. It seems as if Drew must have 
