POLYCHAETE WORMS, PART 1 



163 



debris, the tubes adhering feebly to the rocks. Herpin found that, 

 when available, it feeds on the Enteromorpha as well as on diatoms 

 and filamentous algae and that it may occasionally be carnivorous, 

 capable of attacking and digesting prey larger than itself. Although 

 small, A^. arenaceodonta shows extreme agility, swimming easily and 

 rapidly. 



It has been found swimming at the surface in Vineyard Sound in 

 August (1882, 1902, 1904) and October (1882). It is taken at the 

 surface in both the immature and mature condition. It lacks a 

 heteronereis stage. Specimens were found with relatively few large 

 yolky eggs, about 9 eggs per segment and nearly as great in diameter 



dC 



d ^-^^ "■ h 



Figure 44. — Nereidae, a-e, Nereis succinea: a, parapodium from anterior region; b, para- 

 podium from posterior region; c, parapodium from segment 25 of female heteroncreid; d, 

 compound heterogomph falciger; e, swimming seta of heteronereid. /, Nereis virens, 

 parapodium from middle region of body, g-h. Nereis diversicolor: g, parapodium from 

 anterior region; h, simple neuropodial falcigcrous seta from posterior region, t, Nereis 

 arenaceodonta, parapodium from middle region. 



