POLYCHAETE WORMS, PART 1 161 



coast (including A^. lighti Hartman), and N. japonica Izuka from the 

 Japanese Pacific (see Smith, 1958, 1959) by including them in the 

 same subgenus. The 3 species are morphologically very similar, 

 denoting a possible common ancestry but they may be distinguished by 

 reproductive habit and the morphology of the sexually mature 

 individuals. Also they are reproductively and geographically iso- 

 lated. Hartman (1959a, 1960a) has referred them all to Neanthes 

 diversicolor, an action which ignores the difi^erences in reproductive 

 pattern as well as other differences pointed out by Smith. 



The species of Nereis represented have the body elongate, cylin- 

 drical, tapering anteriorly and posteriorly. Prostomium (fig. 45,a,e) 

 subpyriform in shape, widest posteriorly, tapering and rounded an- 

 teriorly, with 4 eyes on the posterior half. Tentacular segment 

 slightly longer than or up to double the length of the following seg- 

 ments, with 4 pairs of tentacular cirri. Pair of anal cirri of variable 

 length. 



Key to the New England Subgenera and Species of Nereis 



1. Preacicular notopodial lobe elongated, thus provided with 3 notopodial ligules 



(fig. ■i4:,a,f,g,i). Notopodia with homogomph spinigerous setae only 



(fig. 42,e), without falcigerous setae 2 



Without elongated preacicular notopodial lobes, thus provided with 2 

 notopodial hgules (fig. 42,c,d). Middle and posterior notopodia provided 

 with homogomph falcigers in addition to spinigers (fig. 42/i) (subgenus 

 Nereis sensu stricto) 5 



2. Supraacicular neuropodial bundle of setae in posterior region with homogomph 



spinigers and few (1-3) heavy specialized falcigers with end pieces wholly 

 or partially fused to shafts (fig. 44/i) (subgenus Hediste). Upper notopodial 

 ligule triangular, not especially enlarged (fig. 4:4g). Without heteronereid 



stage; spawns in burrows N. (Hediste) diversicolor (p. 174) 



Without fused neurosetae in upper bundle of posterior neuropodia (subgenus 

 neanthes) 3 



3. Basal or oral ring of proboscis with continuous broad band of small denticles 



(fig. 45e). Without heteronereis stage. 



N. (Neanthes) arenaceodonta (p. 162) 



Oral ring of proboscis with denticles in groups, not forming a continuous band 



(fig. 45c). With or without heteronereis stage 4 



4. Parapodia greatly modified in posterior region — upper dorsal ligules become 



elongate, straplike, with dorsal cirri terminal (fig. 446). With greatly 

 modified heteronereis stage, swarms at surface. 



N. (Neanthes) succinea (p. 165) 

 Parapodia not greatly modified anterior to posterior. Upper dorsal ligules 

 broadly triangular, much larger than the other ligules (fig. 44/). With 

 slightly modified heteronereid stage, swarms on flats or at surface. 



N. (Neanthes) virens (p. 170) 



5. Proboscis with paragnaths few in number, lacking entirely on areas vii-viii. 



Parapodial ligules sharply conical (fig. 42/) . . N. (Nereis) grayi (p. 183) 

 ProlDoscis with paragnaths more numerous, present on areas vii-viii ... 6 



6. Parapodial ligules short, thick, evenly rounded (fig. 42d). Body uniformly 



pigmented, not banded. Paragnaths of areas vii-viii with 1-2 irregular 



