256 PROCEEDINGS OF THE ACADEMY OF [April, 



perfectly smooth and iinsegmented. The last three or four thoracic 

 segments are transitional in character to the abdominal. The latter 

 are more distinctly differentiated, owing in part to their more promi- 

 nent parapodia and in part to the greater depth of the ventral furrows. 

 The last few segments are separated by obvious furrows even on the 

 dorsal side. Owing to its being crushed the pygidium cannot be 

 described further than to refer to the pair of prominent, slender and 

 stiff cirri which it bears. A distinct neural groove extends through- 

 out the abdominal region and even on to several of the posterior thora- 

 cic segments. A remarkable smoothness and peculiar dull iridescence 

 characterizes the entire cuticle of this worm. 



If normally formed in this specimen the branchise are highly char- 

 acteristic. All four pairs are large and stout and arise in the usual 

 manner, two pairs anterior and more lateral from II and III and two 

 more posterior and median from IV, those of each side being com- 

 pletely coalesced at the base. A small shield-shaped area separates 

 them in the middle line, but otherwise they cover the entire width of 

 the dorsum. Viewed from above they cover and conceal the entire 

 head and curve downward in front of the prostomium and beneath the 

 tentacles. All are very broad and flat at the base, especially the two 

 inner ones on each side. In the case of three of them the outer one- 

 third is less flattened and tapers to a blunt point. The anterior median 

 of both sides, however, expands into a broad flat plate (fig. 56) some- 

 what lobed on the margins and terminated by a tapering process bent 

 sharply on itself into a hook. This process is complete on one side 

 only, having been broken off of the other. Probably all of the branchise 

 are straight in life, but they are peculiarly stiff and rigid and their 

 cuticular covering is thick and marked by fine transverse strige, but 

 otherwise smooth. 



Thoracic parapodia consist of simple setigerous tubercles arising 

 from the lateral muscular shelf and short auriculate tori with both 

 dorsal and ventral angles produced somewhat freely. Abdominal 

 parapodia (fig. 57) consist of prominently projecting hatchet-shaped 

 ventral tori, each bearing a minute cirriform process, and sharply 

 bent, clavate dorsal cirri which replace the setigerous tubercles of the 

 thoracic region. Parapodia of successive somites are united by a 

 beaded muscular ridge which passes along the side of the abdomen 

 between the torus and cirrus. The worm consists of thirty-two seg- 

 ments, of which II bears the paleoh. III to XIX ordinary setse, and VI 

 to XXXII uncini. 



The paleoli (fig. 58) are of a clear, bright glistening straw color and 



