164 PROCEEDINGS OF THE NATIONAL MUSEUM vol. us 



Distribution: Washington to southern Cahfornia. Intertidal to 

 225 fms. 



Genus Otopsis Ditlevsen, 1917 



Otopsis Ditlevsen, 1917. [Type-species: 0. longipes Ditlevsen, 1917, by mono- 

 typy. Gender: masculine.] 



Diagnosis: Body long, flattened, with lateral parapodia deeply 

 cut. Prostomium small, with 3 small antennae, 2 palps (without 

 palpostyles) . Tentacular segment achaetous, with 2 pairs tentacidar 

 cirri. Parapodia subbiramous. Notopodia with embedded noto- 

 acicula only, without notosetae or emergent acicular setae. Dorsal 

 cirri large, lamelliform. Neuropodia conical, with neuroacicida 

 and simple capillary neurosetae. Ventral cirri lamelliform. Pygid- 

 ium? Proboscis? Integument smooth, not papillated. 



A single species and subspecies have been described : 



Otopsis longipes Ditlevsen, 1917, p. 67. South of Iceland, 843 fms. 

 Otopsis longipes pacificus Uschakov, 1950, p. 171, as 0. longipes var. pacifica. 

 Okhotsk Sea, 709-757 fms. 



Genus Ancistrosyllis Mcintosh, 1879 



Ancistrosijllis Mcintosh, 1879. [Type-species: A. groenlandica Mcintosh, 1879, 



by monotypy. Gender: feminine.] 

 Ancistargis Jones, 1961. [Type-species: A. papillosus Jones, 1961, by original 



designation. Gender: feminine.] 



Diagnosis: Body elongate, depressed, with lateral parapodia deeply 

 cut. Prostomium small, inconspicuous; 2 biarticulate palps with 

 large palpophores and small palpostyles; antennae short, usually 3 in 

 number, consisting of lateral antennae (rarely absent) and posterior 

 median antenna (may be absent). Tentacular segment more or less 

 fused with prostomium, achaetous, with 2 pairs of short tentacular 

 cirri (rarely only 1 pair?). Dorsal and ventral cirri short. Parapodia 

 subbiramous. Notopodia inflated, with notoacicula curved distally, 

 with stout emergent hooked setae beginning on setigers 3-13. Neu- 

 ropodia with conical to truncate setigerous lobes, with neuroacicula 

 and simple neurosetae. Neurosetae variable in length, smooth, finely 

 to coarsely spinous, usually ending in slightly hooked tips (tips may 

 be indistinctly bidentate). Pygidium v/ith paired short anal cirri. 

 Proboscis unarmed, cylindrical, globular, with or without papillae. 

 With intestinal caeca. Integument with scattered papillae. 



Remarks: The chief distinction between Ancistargis and Ancistro- 

 syllis is the absence of a median antenna in the former and its presence 

 in the latter. The median antenna, when present, is small to minute 

 and often difficult to detect. Located as it is on the posterior part of 

 the prostomium, it may be hidden when the prostomium is retracted 

 partially within the tentacular segment. Of the species listed below, 



