122 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



Subgenus NiClDION Kinberg 



Nicidion differs from EunicCj sensu stricto, in that branchiae are to- 

 tally lacking or limited to a few simple filaments in a far posterior re- 

 gion. Like Eunice, it is provided with subacicular hooks and pectinate 

 setae, and it has similar mandibular and maxillaiy parts. 



The affinities of Nicidion and Eunice have already been pointed out 

 (Fauvel, 1930, p. 27; 1932, p. 140). Monro (1933, p. 63) has also 

 emphasized the similarities in referring a species, A'^. kinbergi Webster, 

 as variety of Eunice cariboea Grube. Although the likenesses of the 2 

 groups are great, the species of Nicidion are usually considerably smaller 

 than those of Eunice, the prostomial antennae are proportionately shorter 

 and cirriform, or very weakly ringed, and the masticatory apparatus is 

 more delicate. By definition, branchiae are absent in Nicidion, but in 

 some species, notably N. gracilis Crossland and N. cariboea (below), 

 simple, cirriform filaments may make their appearance in a far posterior 

 region. 



The following species have been reported, or described, from the 

 Western Hemisphere. 



1. Eunice (Nicidion) cariboea Grube (1856, p. 57) from the West 



Indies. 



2. " " y^mZ-er^f Webster (1884, p. 320) from Bermuda. 



3. " " ^r^i;w Ehlers (1887, p. 98) from Florida. 



4. " " fmo^^wfl Monro (1924, p. 61) from Brazil. 



5. " " incerta Hansen (1882, p. 8) from Brazil. (This 

 is very incompletely known.) 



Nicidion edentulum Ehlers (1901, p. 130) from Juan Fernandez 

 and A^. gallapagensis Kinberg (1865, p. 654) from the Galapagos Islands 

 are herein referred to the genus Palola Gray (p. 130), since they lack 

 subacicular hooks and pectinate setae and differ in their proboscidial 

 armature from species of this genus. 



Nicidion is at most a branchia-free form (or nearly so) of Eunice; its 

 separation is here maintained for practical purposes. 



Key to Species of Eunice (Nicidion) 



1. Subacicular hooks absent from a long (about 50 to 55 seg- 

 ments) anterior region; parapodia with ventral pads from about 

 segments 20 to 70 E. (N.) imogena Monro 



1. Subacicular hooks present from about the twenty-fifth to thirty- 

 fifth segment, continued posteriorly; parapodia with ventral 

 pads much farther forward 2 



