856 PROCEEDINGS OF THE ACADEMY OP [DeC, 



in line with the setae bundles of the following somites, is a prominent, 

 stiff, erect cirrus on each side. 



Behind the glandular region the segments become much longer, 

 equaling or exceeding their diameter. These walls are very smooth 

 and thin, highly arched above and nearly fiat below, with thick longi- 

 tudinal muscle bands along the ventro-lateral angles. 



There are eleven setigerous somites, IV to XIV inclusive, but on the 

 left side the bundle of IV is missing. Owing to the flatness of the dor- 

 sum of the region back to X the setse tufts rise up nearly erect from the 

 dorso-lateral margins. Though few, the setae are long and, except on 

 XII to XIV, conspicuous. Uncinigerous tori begin on V and. are 

 short and inconspicuous anteriorly, but about XV begin to increase in 

 prominence, and on the posterior segments, while remaining short, 

 project freely from the ventro-lateral longitudinal muscle bands. On 

 the tori of somites V to X the uncini are arranged in one series, on XI 

 to XIV in tw^o apposed series. Each series on the thoracic somites con- 

 tains about 55 uncini, w^hile on posterior somites (XXX) only 40 occur. 



The setae (fig. 14) are slightly curved, delicate, with narrow wings, 

 almost obsolete on one side and on the other frayed out and then ab- 

 ruptly ceasing, leaving a very acute almost whiplash-like tip. The 

 uncini (fig. 15) have the base broadly rounded in front and provided 

 with a prominent triangular process behind. The sinus is narrow, and 

 from its bottom rises a slender process bearing a very indistinct guard. 

 The beak is rather slender and strongly curved, and above it is a very 

 high crest composed usually of five or sometimes of six transverse 

 rows, of about six or seven each, of long curved spines. The abdom- 

 inal uncini have six or seven transverse rows. 



The single specimen is a female filled with large eggs, and is preserved 

 with a fragment of a soft mucous tube with a slight coating of foreign 

 material. 



It was taken at station 4,279, at Kadiak Island, at a depth of 29 

 fathoms and on a bottom of dark gray mud. 



Thelepus hamatus sp. nov. (Plate XLIV, figs. 16 to 18.) 



An apparently small species known only from the type, an incom- 

 plete specimen consisting of 31 anterior segments, and measuring 21 

 mm. long and 2.5 mm. in diameter at III, thence gradually diminishing 

 caudally. 



The tentacles number very few, less than 15 on each side, but are so 

 fragile that they could not be safely untangled and the exact number 

 ascertained. In the specimen the longest are 13 mm. long, coarse, thick 



