274 PROCEEDINGS OF THE ACADEMY OF [April, 



roughened surface. Slight traces of similar structures continue on 

 to a few anterior abdominal segments. Middle and posterior abdomi- 

 nal segments are marked about the middle in the parapodial zone by a 

 distinct, elevated, glandular ring, the remainder of the body wall being 

 relatively thin and translucent. Pygidium slightly expanded and 

 bent dorsad, the large anus surrounded by a raised border. 



Branchiae two pairs, on somites II and III, when contracted par- 

 tially protected by the lateral wings and dorsal fold. As in Scionopsis 

 pahnata Verrill they are very unequally, asymmetrically and irregu- 

 larly developed. Both specimens have all four present. On the type 

 the right anterior is much the largest and situated exactly in the median 

 line, the left anterior is very small; those of the posterior pair are 

 symmetrical in position and close to the median line, and intermediate 

 in size between those of the anterior pair, that of the left side being 

 slightly larger. The cotype has the anterior left largest, then the 

 posterior right, the posterior left and the anterior right quite small. 

 The well-developed branchiae consist of a rather tall, column-like 

 trunk which at once divides into several (3 to 5) main limbs which 

 diverge and spread more or less horizontally. Each main limb consists 

 of a tapering, strongly zigzag axis which may be traced to the tip and 

 gives rise at each bend to similar lateral branches which also spread 

 horizontally and divide into branches of the third order. Most of the 

 latter bear two to six slender filaments which occasionally bifurcate 

 or divide even farther and are usually (but not always) confined to 

 one side of the branch. Thus is produced a very beautiful and charac- 

 teristic plume-like structure more or less complexly branched according 

 to the size of the gill and having nearly the form of a branch of certain 

 species of the plant Selaginella. The main divisions of the large gill of 

 the type specimen spread symmetrically and are so large that the 

 second pair of gills is completely concealed beneath their posterior 

 limbs, although these are much shorter than the anterior limbs. 



Setigerous tubercles occur on somites IV to XX inclusive, separated 

 from the uncinigerous tori by a slight interval and nearly in line with 

 them. They are nearly cylindrical but somewhat compressed antero- 

 posteriorly. Thoracic uncinigerous tori begin on V and are raised on 

 thickened glandular areas. The first two are longer than the others 

 which are of nearly uniform length. Nephridial papillae exist above 

 those of VII to XVI at least. Abdominal tori are small but prominent 

 and decrease in vertical extent caudad. All are distinctly bilobate, 

 having the angles, especially the dorsal angle, produced, bent forward 

 and free from uncini. 



