1903.] NATURAL SCIENCES OF PHILADELPHIA. 795 



rather stout at the base, tapered gradually to the terminal fourth and 

 then rapidly to a short filamentous ti]) ; they are about twice the length 

 of the head, and the dorsal surface is marked by two longitudinal 

 ciliated lines. No setee occur on the buccal parapodium. The cerato- 

 phores of the tentacular cirri reach beyond the prostomium; their 

 styles are subequal, more than 4 times the length of the head, slender 

 and regularly tapering to fine tips. Crowded between the bases of the 

 tentacular cirri, the prostomium and first elytrophore on each side is a 

 small ovate lobe. The protruded proboscis measures 1.5 mm. long 

 and .7 mm. wide, is nearly terete and bears 13 acute ovate papillae 

 (fig. 6) above and a like number below. Just proximad of these is a 

 circular ridge, terminating on each side in a small prominence. No 

 peculiarities are presented by the interlocking fang-like jaws. 



Besides the peristomium and pygidium there are 25 very distinct 

 setigerous somites in the slender elongated body (fig. 1), which tapers 

 very gently both ways but quite rapidly near the pygidium. Owing 

 to the ver}^ delicate musculature the body walls are thin and inflated 

 and so transparent that even in the alcoholic specimen the entire 

 arrangement of the parapodial muscles is distinctly visible. Except 

 a few at each end, all of the somites are partialh^ biannulate through a 

 cross-furrow just anterior of the parapodia. No nephridial papillae 

 are visible. The small truncated pygidium is slightly annulated, 

 as though composed of several somites, and bears a pair of minute 

 caudal styles above the somewhat dorsally directed anus. 



All of the 25 pairs of setigerous parapodia (figs. 2-5) are uniramal, 

 consisting of neuropodia alone. They are elongated and prominent, 

 those of the middle region very nearly equaling the width of the 

 body. Of a nearly cylindrical form, they are somewhat enlarged at 

 the end, where they terminate in a longer, more pointed presetal pro- 

 cess and a shorter, thicker postsetal process, which is rendered slightly 

 less transparent than the rest of the organ by a small aggregation of 

 gland cells. Toward the ends of the body the parapodia diminish 

 in size, and the last one is a mere short, cylindrical tubercle. ^>ntral 

 cirri occur on all parapodia. They arise from the middle of the ventral 

 surface and are always slender and regularly tapered ; on a few of the 

 anterior somites they reach to the tip of the parapodia, but typically are 

 only ^ as long as their parapodium. 



The dorsal cirri (PI. LV, figs. 1, 2, 5) are borne on all parapodia 

 not occupied by elytra, and because of their unequal development are 

 very characteristic. Each springs from a slight elevation of the body 

 wall above and slightly caudad of the parapodium. The ceratophores 



