BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 73 
sometimes happens that the species is recorded from an absolutely greater number of 
stations of another group than that for which it is here listed. Again, the caution must 
be repeated (cf. p. 31, 33) that in the field a specimen was frequently recorded from a cer- 
tain type of bottom when it seems probable that the dredge, at the moment of taking it, 
was passing over a quite different type of bottom. In many parts of our local sea floor 
several distinct varieties of bottom may be encountered within a quite limited area. 
Nevertheless, we believe that real and important facts of ecology are revealed by 
such tabulations as the foregoing, even though these may not in themselves present a 
complete picture. For concrete illustrations of the assemblage of organisms which may 
actually occur together on a given bottom, or at least within the area traversed during a 
single dredge haul, the reader is referred to the tables on pages 58 to 62. 
Thus far the lists of “‘ prevailing” species for one or another group of stations have 
had no reference to the temperature factor. It has been thought desirable, however, to 
present a list of those species which have been taken at one-fourth or more of the stations 
within the cold-water area of the region, i. e., the area throughout which the water tem- 
perature in summer has been found to be considerably lower than elsewhere. For this 
purpose the Fish Hawk stations (and these only) were chosen, lying, in Vineyard Sound, 
beyond (southwest of) a line drawn from Robinsons Hole to Kopeecon Point, and in 
Buzzards Bay below a line drawn from Barneys Joy Point to Penikese Island. One 
hundred and one stations were included in this area. 
IX. Species taken at one-fourth (25) or more of the stations in the colder waters adjacent to 
the open ocean. 
HypDrRozoa: 
Hydractinia echinata (34). 
Obelia geniculata (27). 
Halecium halecinum (27). 
BRYOZOA: 
Crisia eburnea (43). 
AAtea anguina (25). 
Bugula turrita (70). 
Schizoporella unicornis (46). 
Cellepora americana (30). 
ASTEROIDEA: 
Asterias forbesi (51). 
Asterias vulgaris (58). 
ECHINOIDEA: 
Arbacia punctulata (25). 
Echinarachnius parma (70). 
ANNULATA: 
Harmothoé imbricata (39). 
Nereis pelagica (35). 
Diopatra cuprea (43). 
CIRRIPEDIA: 
Balanus eburneus (37). 
AMPHIPODA: 
Unciola irrorata (27). 
Eginella longicornis (35). 
IsopoDa: 
Idothea phosphorea (26). 
DECAPODA: 
Crago septemspinosus (49). 
Pagurus acadianus (39). 
Pagurus longicarpus (59). 
Libinia emarginata (37). 
Cancer irroratus (75). 
Ovalipes ocellatus (41). 
PELECYPODA: 
Anomia simplex (54). 
Pecten magellanicus (26). 
Mytilus edulis (82). 
Modiolus modiolus (25). 
Arca transversa (60). 
Nucula proxima (30). 
Venericardia borealis (63). 
Astarte undata (51). 
Astarte castanea (44). 
Crassinella mactracea (41). 
Cardium pinnulatum (55). 
Callocardia morrhuana (63). 
Tellina tenera (55). 
Ensis directus (30). 
Spisula solidissima (72). 
