PLANKTON OF THE WOODS HOLE REGION 133 
no larve appeared in the surface collections. From these observations the breed- 
ing season is seen to be much more extended than has hitherto been supposed. 
Occasionally postlarval forms occur after northeast storms. As these are not 
true free-swimming larve they are listed with adults taken under similar conditions. 
During the past year several nonplanktonic annelids have been taken. Certain 
of these may swim freely in their breeding season, but the occurrence in the collec- 
tions was so scattering that I have not considered it as normal. Dodecacera con- 
charum offers a peculiar problem. Scattered specimens, often quite numerous, 
varying from 15 to 20 mm. in length, appeared from July 16 to August 15, 1923. 
The presence of these immature specimens over such an extended period of time 
could hardly have been accidental, and yet Dodecacera is known to be a truly 
benthonic annelid. 
Comparatively few leeches have been taken from the Woods Hole region. 
Sumner records five species, all of which were taken from fish. One species (Ich- 
thyobdella rapax) appeared twice in the surface collections of 1922-23—once on 
January 20 and once on April 7. Both occurrences were during the breeding season 
of the winter flounder (Pseudopleuronectes americanus). Former records give the 
summer flounder as its host, but it is highly probable that it will be found on both 
species. 
The following annelids were taken in 1922-23: 
Amphitrite ornata (Leidy). Nereis pelagica, Linnzeus. 
Arabella opalina (Verrill). N. virens, Sars. 
Autolytus cornutus, Agassiz. Nephthys bucera, Ehlers. 
A. ornatus, Verrill. Odontosyllis lucifera, Verrill. 
A. alexandri, Agassiz. O. sp. 
A. emertoni, Verrill. Pedophylax dispar, Webster. 
A. varians, Verrill. Phyllodoce catenula, Verrill. 
A. longisetosis, Agassiz. P. grénlandica, Oersted. 
Dodecacera concharum, Oersted. Platynereis megalops (Verrill). 
Harmothée imbricata, Malmgren. Podarke obscura, Verrill. 
Ichthyobdella rapax, Verrill. Spio setosa, Verrill. 
Lepidonatus squamatus, Leach. Telepsavus larve? 
Lumbrineris tenuis, Verrill. Tomopterus helgolandica, Greef. 
Magelona rosea, Moore. Unidentified larve of several species. 
Nereis limbata, Ehlers. 
Sagitta is the only true pelagic representative of the phylum Vermes found in this 
region. It usually appears in December and remains until June. In listing the 
Sagittz of past years no attempt was made to distinguish between Sagitta elegans 
and S. serrodentata. The former is more littoral and northern in its distribution, 
while the latter is a southern oceanic form often occurring in the Gulf Stream. 
During the spring of the present year (1923) no specimens of S. serrodentata were 
taken. This may be explained by the fact that the prevailing winds have been 
from the north and comparatively few oceanic forms of any sort have found their 
way in. However, since S. serrodentata forms such an unimportant part of the 
outside plankton, its presence in the region of Woods Hole is, no doubt, so rare that 
the distribution curve of Sagitta for any year can be considered to be the seasonal 
variation of S. elegans. A sudden appearance after July and before November 
