506 PROCEEDINGS OF THE ACADEMY OF [NoV., 



podia. They are slender, filiform and round, often half as long a? the 

 body and with the base constricted so that they are easily detached. 



Dorsal gills usually two pairs, sometimes a rudimentary third one on 

 one or both sides, placed side by side on the dorsum of IV just above the 

 parapodium and a little behind the branchial cirrus. They are slender 

 at the base and swell to about twice the diameter of the branchial cirri, 

 longer than the latter, longitudinally grooved for their entire length, 

 and in contraction crenulate, wrinkled and more or less coiled in an 

 open spiral. 



Setae and spines scarcely differ in form and structure from those of 

 Cirratulus grandis. At the anterior end both notopodial and neuro- 

 podial tufts contain capillary setse only — about 6-8 in each — of various 

 lengths, the longest about two-thirds the body diameter. Spines 

 appear in the neuropodium at about XII, and a few segments farther 

 back each neuropodial tuft contains about four spines and four setse, 

 much shorter than on anterior segments (fig. 14). At the posterior 

 end there are about two of each. In notopodial tufts the setse become 

 fewer and shorter from before backward, but usually spines appear only 

 in those of the posterior one-third. 



Color pale yellow or orange, usually with a greenish tinge, the integu- 

 ments translucent, permitting the dark intestine to show through. 

 Gills and cirri reddish from the contained blood. 



Known only from the deeper waters of Vineyard and Nantucket 

 Sounds, in from 10-19 fathoms, where it lives in colonies among the 

 crevices of Amaroecium pellucidum and in passages of shells. Quite 

 common in the latter at Crab Ledge, ofT Chatham. Nothing definite 

 known of breeding habits, but specimens taken in late August contain 

 small eggs. (Type No. 1657, Academy of Natural Sciences of Phila.) 



This species is easily distinguished from young of Cirratulus grandis 

 of the same size, which are frequently taken under stones at low water, 

 by having but two achsetous segments between the peristomium and 

 first branchial segment. It bears a close superficial resemblance to 

 Cirrhatidus fragilis Leidy, but differs decidedly in that the latter is 

 described and figured as having bifid spines, only one apodous pre- 

 branchial segment, and the branchiae beginning on the second setiger- 

 ous segment. The species recorded under the name Cirrhinereis 

 fragilis Quatrefages as having been dredged in Vineyard Sound, and 

 considered by Verrill to be identical with C. fragilis Leidy, is probabl}^ 

 the species here described. 

 Amphitrite attenuata sp. nov. 



Form slender, clavate, slightly swollen in the anterior thoracic 



