292 THE ANNELIDA POLYCHAETA. 



sides to the middle, but there is no normal triangular process at the middle. 

 On each side the border protrudes forward to embrace the sides of the pro- 

 stomium; the margin of the protrusion is semicircular. From near the anterior 

 border on each side the usual furrow curves ventrad and then more caudoventrad. 

 The lower hp is conspicuously elevated, each of its anterolateral corners being 

 high, free, and rounded; from each of these free corners the anterior margin 

 runs caudad of mesad, as a whole forming a conspicuous obtuse angle, but 

 with the margin a little more depressed at the middle; the surface of the lip 

 is smooth. The tentacular cirri are small, pointed, pale appendages scarcely 

 reaching beyond the caudal edge of the base of the posterior paired tentacle. 

 (Plate 45, fig. 1). 



The first metastomial somite continues smoothly the outhne of the peri- 

 stomium above, its depth being thus clearly greater; and it is also much longer 

 than the peristomium. The depth of the immediately succeeding somites 

 decreases gradually and evenly to the sixth and seventh, where the dorso ventral 

 thickness of the body is least. The second metastomial somite is shorter than 

 the first, the third than the second, and the fourth than the third, after which the 

 lengths are gradually increased again. As the somites decrease in height they 

 become less and less strongly arched above, the somites from near the sixth 

 caudad being but' slightly convex above and being sharply separated from each 

 other by a distinct line, while the more anterior ones are but vaguely separated 

 dorsally. Ventrally the somites are nearly flat, so that the body over most of 

 its length presents a flattened appearance, the dorsoventral diameter being 

 small in comparison with the width. The first metastomial somite is about 

 five eighths as long as the greatest width across the anterior region; and the 

 fourth two fifths to three fourths as long. At the twenty fifth metastomial 

 somite the length has again increased until it is more than half the width {e.g., 

 dr. 11:20). The pygidium was not detected. 



The parapodia of the first pair project strongly forward, as usual, the noto- 

 cirri sometimes extending forward about as far as the tips of the tentacular 

 cirri, or nearly to the posterior level of the lower paired tentacles. The second 

 parapodia extend less forward, the third still less, while the fourth and succeeding 

 ones are essentially transverse. The parapodia of the first three pairs are 

 attached near the anterior edge of their somites and near the ventral level ; begin- 

 ning with the fourth, the parapodia are attached near the middle of the length of 

 the somite and begin to shift gradually dorsad, and with the seventh pair have 

 reached the dorsal level. The notocirrus of the first parapodium is attached near 



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