1914] Treadivell: Poly chaetous Annelids of the Pacific Coast 201 



a small wing along its middle half. Farther back these setae (pi. 11, 

 fig. 17 of the 13th somite) are much stouter and their free portions 

 are scarcely longer than the postsetal lobes. Each has a slight lateral 

 expansion at the point where it leaves the body wall, and tapers from 

 this point to an acute tip. The setae have prominent longitudinal 

 striations. Those in the two lobes of the parapodium are similar, 

 except that the most dorsally placed ones are a trifle longer. 



There are only a few ventral setae. In the parapodium figured 

 there were two sharp-pointed setae on its ventral side, each with a 

 subterminal wing (pi. 11, fig. 19), and one, essentially similar in 

 form, on its dorsal side. Between them are three hooded crochets, 

 having obscure terminal teeth covered by a transparent hood (pi. 11, 

 fig. 20). The dorsal setae, which are similar to those of the anterior 

 somites, are longer and more numerous than the ventral ones. 



Dorsally, a conspicuous white ridge crosses the middle of each 

 somite. 



Collected from San Diego. 



Type in the Museum of the University of California; co-type in 

 the American Museum of Natural History. 



Scolecolepis alaskensis sp. nov. 



PL 12, figs. 21, 22 



No specimen was entire. In the type, a fragment of the anterior 

 end measured eighty millimeters for the first 130 somites. The width 

 of the head, at its base, was five, and that of the second somite, eight 

 millimeters. From here the width gradually increased to thirteen 

 millimeters at the one hundred and thirtieth somite. Another speci- 

 men was considerably larger than the type. 



The head is roughly triangular in form and is divided, by two 

 deep grooves, into a median caruncle-like portion and two lateral 

 areas (pi. 12, fig. 21). There are two tentacles (not shown in the 

 figure) situated in deep depressions at the posterior end of the head. 

 The median caruncle-like area is continued backward between the 

 bases of the tentacles, ending in a slightly elevated free fold. Anterior 

 to each tentacle the outer wall of the groove lies against the "car- 

 uncle," but just in front of each it bends abruptly outward and 

 expands into an elevated wing-like outer wall to the tentacular pit. 

 Each tentacle has an erect bulbous base and a gently tapering terminal 



