1 78 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



clavate, unequal, brancbial cirri, mostly less than four times as long as 

 the diameter of the body. The two anterior segments have slendei- ca- 

 pillary setae in the upper fascicles, less long than the diameter of the body ; 

 they increase in length and numbers farther back, and on the seventh 

 and forty to fifty succeeding segments- they become very numerous and 

 remarkably long, being from two to three times as long as the breadth of 

 the body ; toward the posterior end of the body they again diminish iu 

 length, becoming comparatively short on the last twenty segments. The 

 ventral setfe are all capillary and fine-pointed on the anterior and median 

 segments ; they somewhat exceed the diameter of the body in the middle 

 segments, but are shorter toward both ends. On the last twenty seg- 

 ments there are, in each ventral fascicle, one or two short unciniform 

 setfB Avith somewhat hooked but scarcely bidentate tips. Similar uncini- 

 form setfe exist iu some of the posterior dorsal fascicles. The setse arc 

 silvery white. Body dark olive-green, with lighter dorsal line; branchiae 

 with dark tips. Length, about 25"^ ; diameter, without appendages, 1""" 

 to 1.75"'™. 



Off Campo Bello Island, Bay of Fundy, 60 fathoms, burrowing iu dead 

 shells of Pecten tenuicostaUis, 1872. 



Dodecaceiia concharum CErsted. 



This Species is nearly allied to the last, and occurred with it. It is 

 very common, on our coast, in various shells. The genus Dodecaceria 

 (Ersted has not been distinctly distinguished from Heterocirrus Grube, 

 to which it is closely related. The number of branchial cirri is variable 

 in both, but their arrangement is the same. The setae, however, are 

 different in their arrangement. In I>. concharum the 1st segment bears 

 no setae ; on the 2d to 7th there are short capillary setae, above and 

 below ; on the 8th there is a solitary, long, unciniform seta in the dorsal 

 fascicle of capillary setae, and four or five stouter ones, with bidentate 

 tips in the ventral fascicles, and no capillary ones ; on the 9th and suc- 

 ceedimg segments, the ventral setae continue as on the 8th, and the 

 dorsal fascicles usually contain four or five elongated, simple, hooked 

 micini, together with more or less lumierous fine, acute, capillary seta,-, 

 which are often absent, but they occur on some of the segments even to 

 the posterior end, where they are often about one-third as long as the 

 diameter of the body. Behind the middle of the body the uncini become 

 smaller, shorter, and fewer, only two or three to a fascicle, but near the 

 posterior end, on four or five segments, they become stouter, more hooked, 

 and distinctly bidentate, especially on the ventral side. 



The color is usually dark green or greenish black, and no distinct 

 ocelli were detected, but some obscure dark specks may represent them. 



Praxillura, gou. iiov. 



Body very long and composed of a larger number of segments than is 

 usual in the Malclanidce. Posterior segments Aery numerous, short, l)o- 

 comin^- indistinct posteriorly. Caudal segment subacute, destitute of 



