1909.] NATURAL SCIENCES OF PHILADELPHIA. 283 



Peristomium a short, simple, unsculptured ring incomplete ventrally 

 where it reaches the sides of the mouth. Somite II also a simple ring, 

 but bearing lateral parapodia and bounding the mouth behind. Suc- 

 ceeding somites increase in diameter and become rapidly inflated; 

 III, IV and V are biannulate, with the larger setigerous annulus 

 posterior, the smaller annulus apparently arising in the intersegmental 

 furrow; VI and succeeding somites of the anterior region have the 

 setigerous annulus divided equally by a furrow that appears just 

 behind the setae. Each of the three rings thus formed is divided by 

 short deep furrows into a ring of tessellse or subquadrate areas which 

 are much more conspicuous on the dorsum than on the venter. In 

 the posterior region the interannular furrows become very faint or 

 completely disappear, leaving well-marked simple segments, generally 

 about one-fourth or one-fifth as long as wide and only very obscurely 

 areolated. 



Pygidium a simple, slightly oblique ring which bears no cirri on 

 either the type or cotype. Body walls very thin and readily ruptured. 

 Proboscis partly everted as a smooth broadly trilobed disk. 



Parapodia merely obscure lateral swellings involving the entire 

 length of the somites in the anterior enlarged region and bearing the 

 two well-separated linear tufts of seta? opposite to the middle annulus. 

 Apparently there are no cirri, unless the minute knobs related to the 

 setse fascicles prove to be such. Gills are totally absent. 



Setse colorless with a faint bluish luster, chiefly capillary, of various 

 lengths, curved and slightly flattened distally. Anteriorly they are 

 most conspicuous, forming fan-shaped tufts with linear bases, the 

 neuropodial more spreading, the notopodial longer and curved dorsad; 

 the longest setse about as long as the segment. Posteriorly the setse 

 are fewer and less slender. Short inconspicuous furcate setse (fig. 59) 

 are paired with the capillary setse on all except a few anterior segments 

 on which they cannot be seen. There are no stout setse on II. 



The type, a mature male, and a smaller cotype were taken at Third 

 Beach Point, vicinity of Monterey Bay, by Mr. Spaulding on July 

 6, 1905. 



This species as described differs widely from the type of the genus, 

 especially in the absence of stout setse on II and the absence of neuro- 

 cirri, though it is possible that the latter, like the caudal cirri, may be 

 easily detached. On the other hand the absence of gills and the pres- 

 ence of eye-spots are characters which approximate it to the type, 

 S. minutus Grube. This species would also seem to indicate that the 

 creation of Asclerocheilus as a separate genus is unnecessary. 



