404 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



Genus GAPITELLA Blainville 

 Type G. capitata (Fabricius) 



The thorax consists of 9 segments, of which the first 7 have pointed 

 setae; hooded hooks are present in posterior thoracic segments, some- 

 times accompanied by pointed setae or completely replacing them. Acicu- 

 lar genital hooks replace the hooded hooks in the eighth and ninth noto- 

 podia of male individuals. Rarely there are also a few pointed setae in 

 the eighth segment but their appearance may be irregular. Abdominal 

 parapodia are provided with only hooded hooks. The prostomium is an 

 inconspicuous lobe that lacks eyes ; the nuchal slits are weakly developed. 

 Lateral organs are absent and genital apertures are limited to the last 

 few thoracic segments. There are no specialized branchiae. Nephridia 

 are polymeric in some abdominal segments ; they open into the epithelium 

 and have no distinct external aperture. 



Two species have been reported from the Western Hemisphere : they 

 are the cosmopolitan species, C. capitata (Fabricius) and C. dizonata 

 Johnson, from Washington (see below). A third species, C. ovincola, is 

 herein described as new. 



Isomastus Gravier (1911) is perhaps only a subgenus of Capitella 

 (see Augener, 1932, p. 44) if not congeneric; it is distinguished from 

 Capitella only in that setae as well as hooks may be present in the eighth 

 or also the ninth segment. 



Key to Species 



1. Notopodia of eighth and ninth segments lack setae or hooks in 

 female individuals . . . . . . . C. dizonata 



1. Notopodia of all segments provided with setae or hooks . . 2 



2. Notopodia and neuropodia of sixth and seventh segments or 

 already neuropodia of fifth segment with both capillary setae 

 and hooded hooks; abdominal segments long, length equals 

 nearly 3 times width; abdominal parapodial ridges elevated 

 (pi. 44, fig. 6) C. ovincola 



2. Parapodia of sixth or also seventh segments with pointed setae 

 only ; abdominal parapodial ridges much less elevated. C. capitata 



Capitella capitata (Fabricius) 

 Plate 43, Figs. 1,2 



Fauvel, 1927, pp. 154-155, fig. 55; Berkeley, 1929, p. 312; MacGinitie, 

 1935, p. 693. 



