172 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.10 



4. Endoparasitic; maxillae I simple, falcate, without dentations; 



other maxillary plates weak or with a single tooth .... 



Labidoffnathus, p. 180 



Another genus, Pterothrix Chamberlin (1919, p. 325), was erected 

 for Notocirrus scoticus Mcintosh, but it is believed to be based on frag- 

 ments of 2 species, a Drilonereis and an Arabella (Fauvel, 1923, p. 451). 

 Laranda Kinhtrg (1865, p. 573) is indeterminable (p. 135). 



Genus ARABELLA Grube 

 Type A. iricolor (Montagu) 



Arabella Grube is known from the Western Hemisphere through 

 6 (or 7) species, of which one {A. dubia, below) is doubtfully to be con- 

 sidered here. The most widely present, A. tricolor, has been described or 

 reported under various names from many parts of the Americas; the 

 others are much less known. They are: 



1. A. iricolor (Montagu), p. 173. 



2. A. mutans (Chamberlin), p. 173. 



3. A. semimaculata (Moore), p. 173. 



4. A. setosa Treadwell (1921, p. 113) from Tobago, Jamaica, and 

 other West Indian regions. 



5. A. spinifera Moore (1906, p. 501) from Buzzards Bay, Massa- 

 chusetts. 



A. mimetica Chamberlin (1919, p. 12) from southern California may 

 be distinct, although its identity with A. iricolor (Montagu) has been 

 suggested (Berkeley, 1932, p. 313). Another species, A. dubia Treadwell 

 (1922, p. 160), first described from Samoa, has been reported from the 

 Galapagos Islands by the same author (1928, p. 477) ; since the Samoan 

 specimen is a Drilonereis, the individual from the Galapagos may also 

 not be an Arabella. A. attenuata Treadwell (1906, p. 1172), from Cali- 

 fornia, is also a Drilonereis (p. 177) as shown in the description, "a 

 very broad, bluntly rounded aciculum extends to some distance from the 

 apex [of the parapodium]." 



Three of the 5 species listed above are represented in our collections. 



Key to Species of Arabella 



1. Some inferiormost setae with hooded tip . A. mutans, p. 173 



1. No setae with hooded tip 2 



2. Parapodial lobes short throughout; prostomium with 4 eye- 

 spots; smaller, slenderer A. iricolor, p. 173 



