POLYCH®L LARVAE. 597 
1,000», partly owing to the elongation of the segments 
already formed, partly to growth in the region of 
seement-formation; these specimens, however, appear to 
be less contracted than the Metatrochophore. The whole 
of the body is now segmented, though the two last 
segments (the fourteenth and the anal) do not bear 
parapodia. The remaining segments, however, especially 
those nearer the anterior end, bear appendages which 
show all the characteristics of those of the adult— 
foliaceous large dorsal and smaller ventral cirri, and a 
ramus bearing a tuft of jointed setae of the type shown 
in Pl. II1., fig. 9. In some of the tufts a single capillary 
seta appears to be present also, but I have been unable 
to distinguish with absolute certainty between this and 
the appearance presented by the narrow edge of an 
unusually long distal segment of a compound seta, whose 
proximal segment is entirely embedded in the ramus of 
the parapodium. 
The four tentacular cirri of the first three segments 
have developed unequally, those on the peristomial 
segment and the ventral pair on the second segment being 
now shorter than the other two pairs. The ventral cirri 
of the third segment are not tentacular like the dorsal 
ones, but resemble those of the succeeding segments. 
The prototroch is still conspicuous, and the telotroch 
rather more strongly developed than in the previous 
stage. | 
The pharynx has almost assumed its ultimate 
character. The eyes are very conspicuous. Of cephalic 
tentacles, one pair is visible projecting sideways from the 
anterior end of the head; these are short, slender, and 
very transparent, so it 1s probable that a second pair is 
also present (as in the living specimen about to be 
described) obscured from sight by the tissues of the head. 
