354 PROCEEDINGS OF THE ACADEMY OF [July, 



strong fringe best developed on the shorter blades, which also exhibit 

 an aggregation of some of the terminal hairs to simulate an accessory 

 tooth. On the ventral setae the blades seldom exceed a length of twice 

 the diameter of the end of the shaft, while those of the 3 or 4 setas in 

 the dorsalmost row are narrower and 4 or 5 times as long as the distal 

 end of the shaft. 



Although all of the specimens examined are fully mature and have 

 the body cavity filled with ova or sperm, the alimentary canal is com- 

 plete and well developed, extending continuously from mouth to 

 anus without exhibiting any of that occlusion or degeneration seen in 

 many sexually mature syllids and other annelids. 



The type and about a score of cotypes are No. 1,091 of the Academy's 

 collections. Taken on the "surface in a lead 4 miles from shore by 

 Mr. E. A. Mcllhenny at Point Barrow, Alaska." 



Ammotrypane brevis sp. nov. 



The type of this species is a somewhat contracted specimen 15 mm. 

 long, 1.5 mm. broad and 1.9 mm. high in the middle, being therefore 

 rather robust and tapering to both ends. The general resemblance to 

 A. aulogaster is close, but if the differences exhibited by the single speci- 

 men prove to be constant the two species are readily separated. 



Ammotrypane 6re)'/s.— Parapodium and gill from somite X, X 56. 



Instead of being laterally compressed the prostomium is blunt and 

 flattened dorso-ventrally. From it a slight median ridge passes back- 

 ward and gradually merges into the dorsal curvature of the back. 

 Below this ridge on each side are the small sensory pits or nuchal 

 organs. The mouth is a small trifid opening bounded by a pair of 

 small anterior lobes and a single posterior lobe. Although the body 

 seems to be quite complete and exhibits no indications of regeneration, 

 there are only 29 setigerous somites not distinguishable from one 

 another externally except through the presence of the parapodia. No 

 intersegmental furrows whatever are discernible and the segments pass 

 continuously into one another. Ventrally a pair of stout muscular 

 bands, separated by a deep median groove, produce a somewhat sole- 

 like surface. Above this the body is narrower and strongly arched 



