PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 177 



depressed, narrow in middle, expanding laterally at the front, witli prom- 

 inent, blunt, lateral angles, and with a broadly rounded or sometimes 

 slightly emarginate front margin ; posteriorly the narrow head-lobe ex- 

 tends back to the second setigerous segment. Eyes four, minute, in a 

 quadrangle, the anterior pair wider apart. Antenna? slender, not very 

 long, about three times as long as diameter of body. Buccal segment 

 swollen, forming short, convex, lateral lobes along the posterior half of 

 the head ; lielow the mouth is a prominent, strongly ciliated lobe. Bran- 

 chiae in four pairs, on the 2d, 3d, 4th, and 5th setigerous segments; the 

 anterior pair branched, the others apparently foliaceous and shorter.* 

 The first setigerous segment has a small, prominent, rounded, upper 

 ramus, with few short seta?. The 2d to 5th have a broad linguliform, or 

 leaf-like, upper ramus, with the inner distal edge prolonged into an angle 

 over the back, and a very broad, fan -shaped fascicle of long acute setse 

 set transversely and protecting the gills ; a smaller lobe also exists in 

 front of the setae ; lower ramus composed of a small, rounded lobe with 

 a fascicle of slender sette, and with nncini in the fascicles beyond the 

 15th segment, and a cluster of acute settr. The parapodia increase rap- 

 idly in size from the 1st to the 0th, and then graduaWy decrease to the 

 17th segment, beyond which they are rudimentary ; on the 5th to Sth the 

 upper lingula is about half as long as the breadth of the body ; beyond the 

 5th they are more or less expanded distally, or wide, spatulate, bluntly 

 terminated ; beyond the 10th small, not very prominent, rounded ; on 5th 

 to 10th segments the upper seta? are slender, acute, longer than the lin- 

 gula, and in large fascicles, though in much smaller ones t2ian those of 

 the branchiferous segments ; on the posterior segments the uncini become 

 longer, and the capillary setne mostly disappear in the lower fascicles. 

 Color yellowish or greenish white, often decidedly greenish posteriorly, 

 and with a dark greenish -yellow intestine. Some were filled with pale 

 pink eggs, August 29. 



Cape Cod Bay, 10 to 21 fathoms, soft, foetid mud (U. S. Fish Commis- 

 sion, 1870). 



Heterocirrus fimbriatus, sp. nov. 



A delicate species, remarkable for the great length and slenderness of 

 its seta?, which form a wide fringe along the sides of the body. Head 

 small, about twice as long as broad, not half as broad as the body, ob- 

 tusely rounded in front, with a pair of sublateral ocelli at about the 

 anterior third. Tentacular cirri short, usually absent in preserved speci- 

 mens. The three to six anterior segments bear each a pair of slightly 



*A larger sitccimen was taken in 31 fathoms, off Cape Coil, wbicb maybe a distiDct 

 species. In tbis the brancbiie are long, lanceolate, acute, and all are pectinately di- 

 vided along tbe posterior margin, with slender papilL-e. The eyes are red. Proboscis 

 urceolate, with tbe extended margin scolloped. The first eleven segments bear capil- 

 lary seta-, above and below, in large fascicles ; on the 12tli to 16tli there arc also 

 stouter acute spinules in the lower fascicles ; beyond the IGth segment therQ' are un- 

 cini mingled with the capillary sette. 



Proc. :N^at. Mus. 79 12 IVov. 5. 1 87». 



