POLYCHEZTA FROM THE N.E. PACIFIC. 965 
quite plainly that these two worms from the Atlantic and the 
Pacific must be placed in the same genus. In both the segments 
are broad and flattened, with a glandular dorsal surface raised 
into transverse ridges and traversed by a continuous ciliated 
groove. In both, too, the parapodia are similar, and there is an 
enlargement and incipient modification of the ciliated groove 
to form a cup-shaped organ. ‘There are, of course, minor differ- 
ences, namely, in the development of the notopodia of the first 
segment and in the presence of a rounded lateral border to 
the region without the thin upturned edges which are character- 
istic of W. taylori. 
Text-figure 5. 
A B 
Typical notopodial setze of anterior region. 
A. Mesochetopterus taylori. B. Mesochetopterus minuta. 
The first segment is much longer. The notopodia are even 
less developed than in JZ. taylori—in fact, they are merely clavate 
papille like the second pair of per istomial appendages in Phyllo- 
chetopterus. In the individuals I examined there were two or 
three slender setze embedded almost entirely in the notopodium, 
but projecting very slightly from the surface and ending in a 
slight lanceolate head. 
The neuropodium is a single structure, separated from its 
fellow on the other side by a wedge-shaped prolongation of 
glandular tissue exactly like that described above for J. taylori. 
The uncini contained in the neuropodium are very similar to 
