300 ANNELIDA 



20 pairs of green, short tentacular iilameiits which act as gills; palps 

 large; i)robo.scis unarmed; blood green; setae of the anterior segments 

 o-ften very long and projecting directly forwards: 6 genera. 



1. Trophonia Milne-Edwards. Anterior setae pro- 

 longed, enclosing the head : 2 species in the Woods Hole 

 region. 



T. affinis (Leidy) (Fig. 474). Body slender and 

 elongate; 8 tentacular filaments on head, which are blunt 

 and of unequal length; length 6 cm.; width 3.5 mm.: 

 Vineyard Sound and New Jersey; in 20 fathoms. 



Suborder 6. SABELLIFORMIA.* 



Fig. 474 

 Tro[)honia Prostomium more or less hidden by the forward 



anterior end extension of the peristomium which usually forms a 



projecting collar; tentacles rudimentary or very small; 



palps very large, forming the branchial crown; proboscis present; body 



consisting of 2 regions, a thorax of about 9 segments, and an abdomen ; 



worms tubicolous: 4 families. 



Key to the families of SabelUformia here described : 



tti Tubes membranous 1. Sabellidae 



aa Tubes calcareous 2. Serpuliuae 



Family 1. SABELLIDAE. 



Worms which live in membranous tubes in mud and sand; arising 

 from the prostomium is a pair of large semi-circular feathered gills rep- 

 resenting the palps, which may be surrounded by a collar formed of the 

 peristomium; tentacles rudimentary or hidden; parapodia very rudi- 

 mentary: many genera. 



Key to the genera of Sabellidae here described : 



Oi Peristomial collar present. 



hi Collar lobes separated dorsally 1. Sabella 



6, Collar lobes meeting dorsally 2. Potamilla 



flo Collar absent. 



6i Worms live in gelatinous masses ; no eyes 8. Myxicola 



62 Worms live in distinct tubes ; eyes present. 



Ci Worms in fresh water 4. Manayunkia 



C2 Worms marine 5. Fabricia 



1. Sabella Malmgren. Gill filaments long and slender; peristo- 

 mium raised and reflexed to form a collar around the gills Avhich is 

 notched dorsally: many species. 



* See "Tubicolous Annelids of the Tribes Sabellides and Serpulides from the 

 Pacific Ocean," by K. J. Bush, Ilarriraan Alaska Exp., Vol, 12, 1910. 



