PLANKTON OF THE GULF OF MAINE 35 



in spring. In fact, we have never found the young stages of any bottom-dwelling 

 animals numerically important in the plankton in the basin of the gulf. This fact 

 is interesting because, although the fauna of these deep bottoms is neither so varied 

 nor so rich in actual numbers of specimens as that of the coastal belt, the various 

 mollusks, decapods, worms, and echinoderms that occur there no doubt contribute 

 their larva? to the waters above them, but are so overshadowed by the shoals of 

 Calanus, etc., that only close examination of large amounts of plankton would reveal 

 their presence. 



The phyllopod crustacean genus Evadne deserves mention in this connection! 

 not for any faunal importance in the Gulf of Maine, but because its peculiar life 

 history makes it an infallible index of coastal water, as European students have long 

 recognized (Gran, 1902; Apstein, 1910; Herdman and Riddell, 1911). Probably 

 Evadne, which is seasonal in its appearance in northern coastal waters as a whole, 

 would be found in summer in bays and sheltered waters all around the gulf, for it 

 occurs regularly at the mouth of the St. Croix River in the Bay of Fundy (Willey, 

 1913), on the one hand, and at Woods Hole, on the other. So seldom does it stray 

 seaward in any numbers, however, that the nine stations where it was detected in 

 1915 (the first season when special watch was kept for it, and when towing was 

 carried on from May until October), all lay within 10 miles of land, and most of them 

 closer in. 



In this connection it is interesting that several of the pelagic shrimps 

 (Meganyctiphanes) taken in the eastern basin on August 7, 1915 (station 10304), 

 were carrying numbers of Evadne (among other prey) clasped between their thoracic 

 legs (p. 108), although none of these little Cladocera were taken in the tows made at 

 that station. From what distance could their captors have brought them? 



In an earlier paper (Bigelow, 1917, p. 253) I have briefly summarized the 

 status of neritic copepods in the Gulf of Maine in the following words: 



It is less easy to divide the copepods than other Crustacea into the neritic and oceanic cate- 

 gories, because they are pelagic at all stages. Hence (barring brackish water species), what is neritic 

 in one sea may prove to be oceanic in another. Nevertheless, since they constitute the bulk of the 

 plankton of the Gulf of Maine, I may point out that species which are generally classed as neritic 

 in the North Sea region play only a very subordinate role, if they occur at all, in the central part of 

 the gulf, our summer lists containing only five which are so classed by Farran (1910), [T.] Scott 

 (1911), Herdman and Riddell (1911), and Gough (1905 and 1907); viz, Acartia, Torlanus discaudatus, 

 Cenlropages hamatus, Eurytemora, and Temora. 



We have only one or two records for each of the first four outside the outer 

 islands; none from offshore parts of the gulf (Bigelow, 1914 and 1915). The fifth 

 (Temora longicornis) is apparently less closely confined to coastal waters in the 

 western than in the eastern side of the Atlantic, for in the summer of 1913 it was 

 generally distributed over the gulf (p. 287), though there was no corresponding 

 expansion of other neritic organisms. As a rule it is common only locally near land 

 and over Nantucket Shoals and Georges Bank, a distribution roughly paralleling 

 that of Cyanea. 



Dr. C. B. Wilson's examination of the copepods of the cruises of 1915, 1920, and 

 1921 somewhat enlarges the neritic list at the offshore stations, but supports the 

 general thesis that, as a rule, the more oceanic species greatly predominate outside 

 the outer islands. 



