1909.] NATURAL SCIENCES OF PHILADELPHIA. 281 



and separated by deep intersegmental furrows. Thoracic notopodia 

 and neuropodia bear short, equal, retractile linear tufts of setae, the 

 neuropodia being about twice as far apart as the notopodia and the 

 distance between the latter about equaling the interramal space. 

 Lateral sense organs quite evident, slit-like pores near the caudal 

 border of the segments and nearer to the notopodia than the neuro- 

 podia. 



Abdominal segments very short and much crowded, especially 

 toward the anterior end; posteriorly they are obscurely biannulate 

 and less crowded. Anterior abdominal segments are terete and have 

 thick glandular walls much like the thoracic segments; farther back 

 the walls become thinner and non-glandular and except in the region 

 of the tori the surface is granular, and, chiefly owing to the separation 

 of the tori dorsally and ventrally, the section becomes subquadrate. 

 Anterior abdominal segments have no distinct tori, but bear a con- 

 tinuous line of sessile crochets which appear to completely encircle 

 the segment at the middle. After about the twelfth abdominal seg- 

 ment a slight lateral or interramal break appears and gradually widens 

 until the notopodia and neuropodia become well separated and distinct 

 tori. The neuropodia of each pair remain, however, continuous 

 across the neural surface, but except on a few anterior segments the 

 notopodia are discontinuous and posteriorly become separated quite 

 widely. Lateral sense organs are obscure on anterior abdominal 

 segments, but on middle and posterior segments become distinct though 

 small rounded eminences. Pygidium probably injured as it is divided 

 into several very irregular lobes. 



Gills appear only in the posterior half of the body, usually as two, 

 or sometimes three, short, hollow, sausage-shaped filaments issuing 

 from a pore immediately dorsal to the neuropodium. 



Thoracic setae are exclusively of the usual tapering capillary form 

 with narrowly bilimbate ends. Abdominal segments bear exclusively 

 very numerous crochets of one form in both notopodia and neuropodia 

 (PI. IX, fig. 58). They are slender without a distinct shoulder, but 

 with a subterminal enlargement that tapers to a small head with 

 hooked beak and three small teeth in the vertex of the crest, the end 

 enclosed in a somewhat inflated hood. 



The type was taken at San Diego Bay in December, 1902. 



This species differs from typical members of the genus in having 

 two more than the usual number of thoracic segments. 



