1906.] NATURAL SCIENCES OF PHILADELPHIA. 505 



at the base and in contact with the lower surface of the beak to its 

 tip, above which they arch and recurve in a bold circle (figs. 11 and 12). 



Living color and tube unknown. Filled with eggs on Sept. 2. 

 Taken on two occasions at Crab Ledge, east of Chatham, Mass., in 

 17-20 fathoms, on a stony and gravelly bottom, and not found else- 

 where. (Type No. 1253, Academy of Natural Sciences of Phila.) 

 Cirratulus parvus sp. nov. 



Form very slender, terete, nearly linear, but most slender and attenu- 

 ated posteriorly. Length 20-30 (usually about 25) mm., diameter 

 about .6 mm. Number of segments 60-75. 



Prostomium and peristomium united to form a distinct head (fig. 

 13). Prostomium broad and flat, broader than long, its width nearly 

 two-thirds widest part of body, shaped like the blade of a gravedigger's 

 shovel ; the upper surface with a pair of obliquely transverse sensory slits 

 at the place of union with the peristomiiun ; the ventral surface some- 

 what thickened and divided by a longitudinal fissure. Eyes, one pair, 

 conspicuous, rounded or slightly elongated obliquely, widely separated 

 on middle of head, close to the sensory slits. 



Peristomium a simple, somewhat swollen ring, scarcely differentiated 

 from the prostomium above, but elsewhere clearly defined and forming 

 a straight and smooth lip behind the relatively large mouth. Next two 

 segments (II and III) simple rings with a diameter equal to the peris- 

 tomium and a combined length equalling the entire length of the head. 



Setigerous and branchiate somites begin with IV, which is slightly 

 enlarged. They are at first quite short, but rapidly lengthen without 

 corresponding increase in diameter until the length nearly or quite 

 equals the diameter. Posteriorly they again diminish in length and at 

 the caudal end is a short region of not clearly defined segments. All 

 somites simple and uniannular, and the intersegmental furrows smooth 

 and clear cut. Although the body is nearly terete the ventral surface 

 is somewhat flattened and the parapodia somewhat projecting. Pygi- 

 dium bearing a minute pointed projection below a nearly circular, 

 dorsal anus. 



Parapodia begin on IV and continue to posterior end; they are small, 

 ventro-lateral projections bearing separate notopodial and neuropodial 

 tubercles. 



Branchial cirri also begin on IV just above the parapodia, and a pair 

 occurs on each segment for about twenty, after which they are borne on 

 every second or third segment and finally more scatteringly nearly to 

 the posterior end. Cirri of the middle and posterior region are borne 

 at the posterior margin of the segments some distance above the para- 



