SABELLIDES AND SERPtfLIDES 193 



8'. Collar with ends meeting or in contact on back. 

 Incisions or clefts dorso-lateral and ventral. 



Avicular uncini in tori on abdomen ; avicular uncini and pennoned setae in tori 

 on thorax. 



(33) POTAMIS Ehlers 1887. 



Type, P. spatkiferus Ehlers 1887, figures. Off the coast of Florida, 

 In 275 fms. 



Branchial lobes small ; branchiae free, unequal. Inferior setae on 

 thorax, below collar fascicle, orbicular in form. Avicular uncini on 

 thorax in form intermediate between those of Jastnineira (as in J. 

 oculata Langerhans 1884) and those of Pseudopotamilla (as in P. oculif- 

 eraLeidy 1855). 



(34) PSEUDOPOTAMILLA gen. nov. (Potamilla Malmgren 1865, in part). 



(Seep. 203.) 



Type, P. reniformis (Leuckart 1849, figures, + Malmgren 1867, fig- 

 ures). Iceland. 



Branchial lobes small; branchiae simple, free, equal. Inferior setae 

 on thorax, below collar fascicle, spatulate in form. 



(35) SCHIZOBRANCHIA gen. nov. (See p. 205.) 



Type, 5. insignis sp. nov., figures. Alaska. 



Branchial lobes small; branchiae free, divided. Setae similar in form 

 to those of Pseudopotamilla. 



(36) EUDISTYLIA gen. nov. (See p. 209.) 



Type, E. gigantea sp. nov., figures. Alaska. 



Branchial lobes produced ventrally, forming equal spirals; branchiae 

 In nearly uniform double series. Setae similar to those of Pseudopota- 

 milla, i. ., inferior setae on thorax, below collar fascicle, spatulate in 

 form. 



Genus Sabella Malmgren 1865. 



Type, Sabella pavontna Savigny. 



In this genus the branchial lobes are small at base, free and more or 

 less prolonged ventrally, spirally coiled or involute in retraction, more 

 or less flaring when fully expanded. 



The branchiae are nearly equal in length, arranged in a single series, 

 their rachises four-sided, being flattened on the back, the two outer 

 angles furnished with thin membranous edges, most developed and 

 sometimes ruffled along their anterior or distal portions, where they 

 frequently fold outward, toward each other, forming a conspicuous 

 groove. The two inner edges bear slender, more or less crowded pin- 

 rue which do not extend to the end, leaving a thin, flattened, more or 

 less bluntly rounded tip. They arc connected along their posterior or 

 proximal portions by a more or less developed, thin, intcrbranchial 

 membrane or web. Eyes usually present, arranged in pairs on the 

 back, often concealed by color spots. 



