PLANKTON OF THE WOODS HOLE REGION 131 
the Fisheries dock. In this case, as in the case of NV. limbata, free-swimming larvee 
appeared in great numbers in the tow, but few adults were taken. The usual 
swarming season for N. limbata ranges from June to September. A few adults of 
NV. pelagica were taken during the year, but none of these contained ripe sex products. 
The breeding season of this species is in August and September. Platynereis 
megalops is also commonly taken at the surface from July to September. Although 
the young were taken on several occasions, but one adult appeared in the collections 
July, 1922 
August 
Jane, 1923 
September 
October 
November 
December 
November 
Decenber 
Amphitrite ornata 
Arabella opalina 
Autolytus cornutus 
Autolytus ornatus” 
Autolytus alexandri 
Autolytus emertoni 
Autolytus varians _ 
Autolytus longisetosis 
Dodecacera concharum 
Harmothoe imbricata 
Ichthyobdella rapax 
Lepidonatus squamatus 
Iarval Lesquamatus 
Lumbrineris tenuls 
Magelona rosea ~ 
Nereis limbata 
Nereis pelagica 
Nereis virens 
Nephthys bucera 
Odontosyllis lucifera 
Odentosyllis spe 
Paedophylax dispar 
Phyllodoce catenula 
Phyllodoce gronlandica 
Platynereis megalops 
Podarke obscura 
Spio setosa- 
Telepsavus larvae 
Tomopterus helgolandica | 
Unidentified larvae stoi 
Fic. 33.—Occasional occurrence of annelids in surface collections from June, 1922, to May, 1923. 
@, single specimen taken 
of the past two summers. All of the members of this family undergo extensive 
physical changes in adapting themselves for pelagic life during the breeding period. 
The anterior, nonsexual part remains the same, but in the posterior, sexual region 
the parapoda become broad and flat and the chete increase greatly in length. 
In this form the worm is known as Heteronereis and is able to swim very rapidly. 
In contrast to the Nereide stand the families Syllide and Hesionide. The 
different species of Autolytus carry their eggs and swim about for varying lengths 
