ONUPHIS NANNOGNATHUS. 271 



ceratophore is also of nearly the same thickness and length as that of the adjacent 

 paired ones; it consists of five very short articles, of which the most proximal 

 is somewhat larger than the others, and a smooth distal division which is de- 

 cidedlj^ more than one third of the total length. The style is like that of the 

 adjacent paired ones. 



The peristomium is much thicker than the prostomium, being conspicu- 

 ously higher, the dorsal surface rounding up from the anterior edge to the caudal. 

 On each side the border protrudes forward convexly and embraces the sides of 

 the prostomium. The lower lip is strongly and abruptly elevated and then 

 sharply set off both laterally and caudally ; the anterior margin is mesally deeply 

 excised, the excision broadly V-shaped, with the outer part of each side curving 

 ectad. The cirri are long and slender, each extending beyond the distal ends 

 of the ceratophores of the tentacles. 



The first metastomial somite is higher and much longer than the peri- 

 stomium. The second and third metastomial somites are shorter than the first 

 and about equal to each other, and they are high and strongly convex like the 

 first, though the dorsum of the third slopes somewhat downward caudad. The 

 dorsum of the fourth continues the downward slope. At the sixth or seventh 

 somite the minimum depth of the body is attained, the dorsum of these and 

 succeeding somites being only slightly convex and crowned by a shallow median 

 longitudinal furrow. The venter throughout is weakly convex, and is traversed 

 by a conspicuous neural groove. The glandular area, prominent on each side 

 of all but the most anterior somites, is tyj^ically very elongate transversely, 

 with the mesal end narrowed more or less to a point. From about the twenty 

 fifth somite the body narrows forward, the narrowing at the anterior end being 

 very strong; caudad the width remains nearly uniform to the end of the frag- 

 ment. The first somite is about three fourths as long as its greatest width 

 exclusive of the parapodia; the second one half as long as wide; while the twenty 

 fifth and succeeding somites, which, hke all excepting the first few are very 

 short, are about nine times wider than long. 



The parapodia of the first three pairs are attached at the anterior border 

 near the ventral level and, as usual, are directed somewhat forward, those of the 

 second and thu-d pairs somewhat less so than the first ones. These parapodia 

 are stout, cylindrical, and moderately long. Beginning with the fourth parapo- 

 dia they are attached near the middle of the length of the somite, project trans- 

 versely, and begin a shift dorsad, so that by the twelfth they are at the dorsal 

 level; at the same time the parapodia undergo a decided shortening. In the 



