POLYCHAETE WORMS, PART 1 289 



Abdominal region \vdth long, straplike paired branchiae. Long, 

 ligulate postsetal notopodial lobes (may become longer than branchiae) , 

 with a ciHated ridge near the inner side (the paired ciliated branchiae 

 and paired ciliated notopodial lobes thus form 3 longitudinal ciliated 

 grooves along the body). Slender, digitiform interramal cirri at bases 

 of the neiu-opodia (usually begin on last few thoracic segments, con- 

 tinuing on 44-50 or so segments). Bilobed neuropodia, the inner lobe 

 elongated, ligulate, the outer lobe small, rounded. In transitional 

 region, 3 extra postsetal and subpodal papillae on last few thoracic 

 (2-6) and first few abdominal segments (2-9), then with entire, broad, 

 foliaceous subpodal flanges uniting the neuropodia with the sides of 

 the body. The outer border of the flanges may be flaring or undulate 

 but not incised (as in the closely related S.fragilis, fig. 7Qg). 



Proboscis, when fully extended, forming a large voluminous, multi- 

 lobed folded sac, divided into 5 main lobes, each of which is again 

 divided into 3-4 long, slender, secondary lobes, convoluted at the 

 margins, united at the base by a delicate web. In life the processes 

 are continually changing their form (Moore, MS.). Color: orange-red, 

 orange-3^ellow, with red middorsal blood vessel and branchiae. 



Biology, — Found in vertical burrows in sand, muddy sand, sandy 

 mud, gravell}^ sand, or mud. Dredged in rather shallow water on 

 bottoms of fine sand and sandy mud. They break up easily when dis- 

 turbed. They may be associated with the closely related S.fragilis, 

 but attain a much larger size than the latter species. 



The early development has been followed by Horn and Bookhout 

 in the Beaufort, North Carohna, area. Mature worms are found in 

 May through September. Apparently the females eject the eggs 

 freely, not forming gelatinous egg cases as do some species in the 

 family. The eggs develop into typical trochophores and ciliated larvae. 

 After a short swimming stage of about 3 days, ciliation is lost and the 

 larvae metamorphose. Juveniles of 7 days have 11 segments (8 

 setigers, first 2 and last segments achaetous), a pair of eyespots, 2 

 pairs of branchiae beginning on segment 10 (setiger 8). In maturing 

 to the adult, branchiae would be lost, as in the adult the branchiae 

 begin on about setiger 26 (16-32). 



In the Woods Hole area, Massachusetts, it breeds in early July, 

 probably throughout the summer (Moore, MS.). Many small ones 

 were found in August (North Falmouth, August 24, 1950). In Maine, 

 females massed with dull pinkish or orange eggs and males with white 

 sperm masses were found in June and July (Woodbridge Island, 

 June 29, 1955; Cape Newagcn, July 8, 1955). 



Material examined. — Numerous specimens from Gulf of St. 

 Lawrence (Prince Edward Island), Nova Scotia (Lawrencetown and 

 head Green Harbor, Halifax County; Peninsula leading to Caribou 



