POLYCHJETA 



287 



tentacles, 2 palps, and 4 eyes; peristomium with 2 cirri on each side; 

 reproduction normally by asexual budding: numerous species; abundant 

 in clean, shallow water among hydroids, mussels, and tunic ates. 

 Key to the genera of Syllidae here described: 



Oi Palps prominent ; ventral cirri present ; tentacles and cirri segmented. 



1. Syllis 

 ventral cirri absent ; tentacles and cirri filiform. 



2. AUTOLYTUS 



Oa Palps rudimentary 



1. Syllis Savigny. Tentacles and cirri segmented, the latter often 

 terminally dilated; palps large; new individuals formed by terminal, 

 and in case of Syllis ramosa, lateral budding: numerous 



species, 2 in the Woods Hole region. 



S. pallida Verrill. Body slender, tapering at both 

 ends, 15 to 25 mm. long; color white: 

 Long Island Sound to Bay of Fundy; m 

 mud, sand, and on shells, from low-water 

 mark to 30 fathoms. 



2. AuTOLYTTJS* Gi^ibe. Tentacles and 

 cirri not segmented; palps rudimentary 

 or absent; ventral cirri wanting; the 

 young individual acquires a head before 

 separating from the parent, and a num- 

 ber may be present in a row; males and 

 females differ in appearance: numerous 

 species, 6 in the Woods Hole region. 



A. cornutus A. Agassiz. Length 15 

 mm. ; color pmkish ; full-grown male hav- 

 ing 30 segments, female 40 to 50 seg- 

 ments: New Jersey to Bay of Fundy, 

 from low-water mark to 15 fathoms; 

 common. 



A. varians Verrill (Fig. 457) . Length 

 15 mm.; intestine with bright-red spots which can be seen through the 

 body wall: North Carolina to Maine, often among hydroids. 



/' 



Fig. 457 



Fig. 458 



Fig. 457 — Autolytua varians 

 (Mensch). 1, tentacles; 2, peri- 

 stomial cirri ; 3, budding individ- 

 uals. Fig. 458 — Podarl-e ohscura 

 (Verrill). 



Family 4. HESIONIDAE. 



Body rather short and often cylindrical; parapodia usually unira- 



mous and with ^ jointed dorsal setae; 4 eyes, 2 or 3 tentacles, and 



2 palps on tht )stomium; peristomium with long cirri: species not 

 numerous. 



* See "Auto' s," by P. C. Mensch, Jour. Morph., Vol. 16, p. 269, 1900. 



