418 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.10 



Notopodial tori are much more elevated and prominent, especially in 

 posterior segments, but they are much shorter than the neuropodial ones 

 and contain a much smaller number of uncini. 



Branchiae were described as low, rather long, inconspicuous folds. 

 Abdominal hooks are shown with a strong fang, nearly at a right angle to 

 the main stem and surmounted by a semicircle of 8 or 9 small teeth above, 

 designated a depressed hood (crest as herein used). A hyaline sheath or 

 hood is presumably absent. 



In several important respects this individual is thus strikingly dif- 

 ferent from N. magnus (see above). The pattern of the proboscis, 

 thoracic epithelium and abdominal parapodia are notably different. 

 Hooded hooks of the abdomen are distally provided with a main fang 

 overarched by only 8 or 9 denticles. Even if the branchiae were com- 

 pletely retracted in this individual, which is not unlikely, and were thus 

 not described, there are still other significant differences between 

 N. giganteus and N. magnus, especially in the lateral organs and neph- 

 ridia, the segmental grooves of the abdomen, the proboscis and the ab- 

 dominal hooks (see above). 



A more complete knowledge of the species, "N. giganteus, depends 

 therefore either on reexamination of the holotype specimen or a redescnp- 

 tion based on collections from the type locality. 



Subgenus CLISTOMASTUS Eislg 

 Type Notomastus (G.) lineatus Claparede 



This agrees with Notomastus (sensu stricto) in many respects except 

 that nephridial apertures are limited to a few posterior thoracic segments, 

 or are reduced or even absent. Abdominal hooks are hooded; the fang 

 is straight and slender or somewhat recurved and surmounted by a crest 

 of 5 (rarely 6) teeth in a single or alternating transverse row. The 

 shaft is fibrillated throughout its length except for a soft, slightly granu- 

 lar base. 



Only one species, N. (C.J lineatus (see below) has heretofore been 

 referred to this genus. Two others, N. tenuis Moore and N. luridus 

 Verrill are newly ascribed to it and a fourth, N. hetnipodus, is newly 

 described. A fifth species, known as Eisigella ouanaryensis Gravier 

 (1902, p. 266) may also belong here. The genus Eisigella Gravier is 

 known through this single species and is said to differ from Notomastus 

 only in that nephridial pores are either absent or rudimentary. This 



