424 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



According to Verrill ( 1873) color in life is dark purplish brown with 

 a bluish iridescence anteriorly and a darker median dorsal line posteriorly; 

 the surface is strewn with minute white spots. 



This species is herewith referred to the subgenus Clistomastus because 

 nephridia are seemingly either vestigial or absent; abdominal hooded 

 hooks are similar to those in the other species of Clistomastus that have 

 been examined but in this species the hooks are unique in that the 5 teeth 

 in the crest are not in a straight row but 2 have been displaced upward 

 to form a second, alternating row. 



I am indebted to Dr. Stanley Ball of the Peabody Museum of Natural 

 History at Yale University for the loan of materials on which this 

 redescription is based. 



Distribution. — Notomastus (Clistomastus) luridus is known from 

 localities in New England south to New Jersey, from intertidal zones. 



Notomastus (Clistomastus) hemipodus, new species 



Plate 48, Figs. 1-5 



Collections. — Numerous individuals come from the vicinity of Beau- 

 fort, North Carolina; some were dredged from shallow waters in Bogue 

 Sound, others come from muddy sand shoals exposed at low water near 

 the mouth of the Newport River and from Bird Shoal. 



In size this species is intermediate between the other capitellids with 

 which it occurs, including the smaller Heteromastus filiformis (Clapa- 

 rede) and the larger Dasybranchus lumbricoides Grube. Length of 52 

 segments (posteriorly somewhat incomplete) is about 30 mm; the maxi- 

 mum width in the thorax is 1.5 to 1.7 mm. The epithelium of the thorax 

 is somewhat areolated through only the first 5 segments ; the last 7 seg- 

 ments are increasingly smoother. The body is slightly arched upward in 

 its anterior portion as in other capitellids. The abdomen is nearly 

 smooth except for the glandular ridges and transverse wrinkles of con- 

 traction. 



The prostomium is an elongate, triangular, somewhat depressed lobe ; 

 its anterior end is prolonged in a slender palpode. Its dorsal surface 

 near the posterior margin has 2 minute, dark red eyespots and a pair ot 

 nuchal slits that are to be seen only by pushing back the peristomial fold. 

 The proboscis, everted in some individuals, is closely papillated on its 

 proximal half but the distal part is smooth and covered with a thin 

 membrane. 



