POLYCHAETE WORMS, PART 1 255 



Branchiae begin on about setiger 25 (18-33), beginning as a small 

 simple cirriform filament at the bases of the dorsal cirri, becoming 

 longer, slender, equal to about a half to three-fourths of the body 

 width, continuing as a simple filament to near posterior end. Ventral 

 cirri on fu-st 3 setigers short, subulate, about same length as dorsal 

 cirri; on setiger four, short, conical; from setiger five on, forming low 

 cushioulike lobes. Setae of fu'st setiger consist of few heavy dark 

 amber-colored curved acicular setae, tapered to blunt tips. Setae of 

 second setiger acicular, pointed, flared distally to a frayed or pectinate 

 tip. Rest of parapodia of prebranchial region with (1) limbate setae 

 with pointed tips and (2) short delicate pectinate setae. Parapodia 

 of branchial region with lobes conical and, in addition to the above 

 2 types of setae, with 2 stout bidentate acicular hooked setae and 

 usually 3 projecting acicula; setae and acicula light amber colored. 

 With 2 long filiform anal cirri on ventral side of furrowed anal ring. 



Proboscis with a pair of calcified white winglike mandibles. 

 Maxillae light amber colored, with a pair of embedded short oval 

 maxillary carriers; maxillae i, hooked forceps; maxillae ii with about 

 13 teeth (12-17); left maxilla iii with about 12 teeth (8-18), right 

 maxilla in missing; maxillae iv forming anterior cmwed rings with 

 about 10 teeth (4-11) ; maxillae v rudimentary or with a single tooth. 



Tube: Free, unattached, cylindrical, firm, tough, transparent, quill- 

 like, colorless or yellow, open at both ends; sufficiently transparent 

 so the large iridescent worm can be seen within. The tube tapers 

 gradually, with one end larger than the other (the anterior end of the 

 worm is at the larger end of the tube). Wall of the tube thickest in 

 the middle, where it may be very thick and tough, difficult to cut, 

 diminishing in thickness toward the gently curved and tapered larger 

 elliptical end where it is thin and semicollapsible. Tube composed 

 of successive layers of a tough secretion and is marked by faint 

 annular rings; both orifices guarded from intrusion by several pairs 

 (usually 3 pairs) of soft membranous valves, closing the opening but 

 aUowing the occupant to move out. 



Biology. — Dredged on bottoms of soft mud, sand, mud mixed with 

 pebbles, gravel, rocks, shells. The free tube in which the worm lives 

 evidently lies free on the surface, the worm protruding from the tube 

 and dragging it about. The tube may be slick and clean or it may 

 have other organisms attached to it, as hydroids, anemones, sponges, 

 barnacles, and tunicates. 



Material examined. — Numerous specimens from off Massachu- 

 setts to off North CaroHna, West Indies, Gulf of Mexico, 67 to 966 

 fathoms. 



Distribution.— A cosmopolitan species in abyssal depths. Green- 

 land, Norway, North Sea, English Channel, off Canaries and Azores, 



