SABELLIDAE. 409 



//. Collar with four lobes; eyes not subteriniiial SaheUa Liiine. 



ee. Dorsal setae of thorax of two kinds. 

 /. Abdominal setae of but one kind. 

 g. Collar two-lobcd. 



/*. Collar with ends dorsally separated Parasabella Bush. 



hh. Collar with ends in contact above Potamilla Malmgren. 



gg. Collar four-lobed. 



h. Branchiae simple Pseudopotanillla Bush. 



hh. Branchiae dichotomously divided from one to six times. . . .Schizobranckia Bush. 

 ff. Abdominal setae of two kinds. 



g. Setae of first somite in linear rows. 



h. Collar onc-lobed Protulides Webster. 



hh. Collar two-lobed Hypsicomus Grube. 



gg. Setae of first somite forming an ordinary small fascicle on each side; posterior 



base of avicular micini very long Potamethus, nom. nov. 



cc. Collar none or rudimentary. 



Dorsal thoracic setae of one kind Amphiglena Claparede. 



bb. Thoracic tori bearing avicular crochets forming a single row and long-stemmed rostrate crochets 



adjacent to these Laonomedes, gen. nov.^ 



1. Thoracic tori bearing a single row of setae, these being crochets of one kind, — pectinate, avicular 

 or rostrate. 

 6. Crochets avicular both on thorax and on abdomen, 

 c. Branchiae with dorsal (outer) appendages; dorsal thoracic setae of a single kind. 



d. Collar four-lobed Dasychone Sars. 



dd. Collar two-lobed Dasychonopsis Bush. 



cc. Branchiae without outer appendages. 

 d. Dorsal thoracic setae of two kinds. 

 e. Setae lacking on first somite. 

 /. Posterior base of uncini truncate; collar with ends separated. . . .Laonome Malmgren. 

 //. Posterior base of uncini prolonged; collar with ends in contact. .Paralaonome Bush. 

 ee. Setae in a double angular series on first somite; posterior base of uncini ordinary. 



Notaulax Taubcr. 

 dd. Dorsal thoracic setae of one kind. 



e. Branchial lobes on each side forming a double concentric semicircle. 



Sabellastarle Savigny. 

 ee. Branchial lobes not thus arranged. 



/. Collar well developed; branchiae united by a membrane Eurato St. Joseph. 



ff. Collar obsolete; branchiae free Euratella, gen. nov.^ 



66. Crochets of thorax with long manubria. 



c. Crochets of abdomen with long manubria; dorsal thoracic setae of one kind (an inner 

 pair of longer tentacles; abdominal soiiaites only three). 

 d. Branchial lobes laterally elongate, bearing numerous ciliated branchiae and seven eye 

 spots on each side; seventh somite specially modified, longer than the others and ante- 

 riorly expanded Manayunkia Ixudy. 



dd. Brancliial lobes not thus extended laterad, eye spots one or none on each side; seventh 

 somite not specially modified, 

 e. Branchial lobes small, bearing few ciliated branchiae; one distinct eye spot on each lobe 



in both sexes Haplobranchus Bourne. 



ee. Branchiae numerous; eye spots none in male, a rudimentary pigment spot on each 



brain lobe in female Dybowscclla Nusbaum. 



cc. Crochets of abdomen not with long manubria, pectinate or avicular uncini recalling often 

 those of Serpulidae and Terebellidae. 

 d. Branchiae united by a slight membrane over most of length. 

 e. Without protruding uncinigerous tori. 



An almost complete girdle of very small uncini on abdomen. Dorsal thoracic setae 

 of one kind My.ricola Koch. 



'Genotype. — Laonome aniarctica (Kinberg). 

 ^Genotype. — Laonome salmiddis (Claparede). 



