POLYCHAETE WORMS, PART 1 49 



tips; rest compound, some having short terminal blades with bifid 

 hooked tips and with shafts strongly to faintly spinous distally; 

 others having long, pseudoarticulated terminal blades with bifid 

 hooked tips and with distal part of shafts spinous, ringed, or smooth. 

 Color: delicate flesh color, translucent. 



Biology.— Found intertidally burrow^ing in loose sand, gravelly 

 sand, muddy sand, and clay. Dredged on bottoms of sand with shell 

 fragments and stones. 



Material examined.— Massachusetts (Cape Cod, Provincetown, 

 Truro, Wellfleet, Barnstable; Nobska, Woods Hole; Edgartown, 

 Martha's Vineyard), Connecticut, Long Island Sound, Georgia 

 (Sapelo Island), in low water to 19 fathoms. 



Distribution.- — Massachusetts (Cape Cod) to Georgia. In low 

 water to 20 fathoms. 



Genus Sthenelais Kinberg, 1855 



Type (monotypy) : Sthenelais helenae Kinberg, 1855. 



Both species burro\ving forms, with the body prismatic in cross 

 section, flattened ventrally, convex dorsally, tapering gradually 

 posteriorly. Without dorsal cirri on segment 3, with 2 medium 

 long anal cirri, with ventral cirri about the length of the neuropodia. 

 Elytra numerous pairs, imbricated, covering the dorsum. Pro- 

 stomium suboval, with rounded ciliated nuchal organs at posterior 

 angles. Four eyes arranged in square near the base of the median 

 antenna, the anterior pair partl}^ hidden. Median antenna with stout 

 ceratophore which has a pair of antennal ctenidia attached basally 

 and flaring distally (fig. 106); style of median antenna rather long, 

 tapering, smooth; paired palps very long, tapering, smooth. 



Tentacular segment with dorsal pair tentacular cirri about same 

 length as median antenna and a shorter ventral pair, with numerous 

 fine setae; with a pair of small prostomial lateral antennae fused 

 basally to the inner dorsal part; with a pair of medial buccal ctenidia 

 composed of a foliaceous plate medial to the tentacular cirri and 

 forming a short delicate sheath or sleeve around the base of the palps, 

 Cirriform branchiae begin on segment 4; mth parapodial ctenidia in 

 groups of 3 in the concave area above the notopodia (fig. 10c). Noto- 

 podia wdth fringe of short to long papillae (parapodial stylodes), with 

 numerous setae curving dorsafly; notosetae simple, capillary, finely 

 spinous. Neuropodia with conical acicular lobes surrounded by para- 

 podial bracts with fringes of papillae. 



Neurosetae of several kinds: (1) Upper group of few setae simple, 

 spiraUy spinulate, tapering to fine tips; (2) a horseshoe-shaped middle 

 group of compound setae around the acicular lobe, some or all of 

 which have the terminal blades short and bifid hooked (compound 



