3904.] NATURAL SCIENCES OF PHILADELPHIA. 161 



teeth along the profile. The pick-shaped imcini (fig. 6) are more char- 

 acteristic. They have slender, slightly curved stems, shghtly increasing 

 in diameter toward the distal end, and exceed the total length of the 

 avicular uncini. The head is small, with a rounded back, and a short 

 blunt beak, enclosed in a delicate and transparent hood, the base of 

 which is often inflated, and the distal part prolonged at right angles 

 to the stem into an exceedingly delicate and attenuated process, which, 

 though varying considerably in length, always much exceeds the length 

 of the head of the avicular uncini. The latter only occur on the ab- 

 domidal somites, where they form short vertical series of from 12 to 18. 

 Except that the upper outline of the breast is more sloping, they have 

 exactly the form of the thoracic ones. 



In the form of its setse this species closely resembles Sahella {Pota- 

 ■milla?) assimilis Mcintosh, but the pick-shaped uncini of that species 

 have not been described. It was dredged by the Challenger in 600 

 fathoms off Buenos Ayres. It also agrees fairly well with the Pota- 

 milla torelli of Marenzeller and Langerhans, but not with JMalmgren's 

 original description. 



The tube is circular and tortuous, of a tough cartilaginous consistency, 

 covered evenly with very fine sand and has a clear line, evidently of 

 attachment, along one side. 



Sagami Bay, 3,698, 153 fms., 2 specimens and fragments of a third, 

 with tubes. 



Hypsicomus lyra n. sp. (PI. XI, figs. 7-13; PI. XII, fig. 42.) 



The type is very long and slender, having a total length of 84 mm., 

 the thorax 6 mm. and the gills 20 mm. ; the diameter is 1.6 mm. 



As seems to be usual in the genus, the basal lobes of the gills are 

 quite prominent, about equalhng the length of the first 3 somites, 

 and their somewhat membranous dorsal and ventral margins overlap 

 in the middle line. The distal end is strietl}^ transverse and even, so 

 that the radioles all arise from the same level. The radioles are long, 

 slender, straight, not winged, and united by a web for the basal |. 

 The double-ranked barbs are very numerous, slender and long, their 

 length about equalhng the diameter of the bod}^, l^ut diminishing some- 

 what before the short, naked tip of the radiole is reached. A con- 

 spicuous zone of reddish-brown eye-spots occupies about the third -^-^ 

 of the branchiae, though they exhibit much irregularity in arrangement, 

 and seldom occupy this entire distance on individual radioles. Each 

 radiole bears a series on each outer luargin, but the number varies from 

 5 to 20 or more, and they may be widely separated, jnuch crowded or 

 11 



