PLANKTON OF THE GULF OF MAINE 



239 



On the American side Willey (1919) lists it at one station in the Gulf of St. Law- 

 rence and one just outside the continental edge of Le Have Bank off Nova Scotia, and 

 the Michael Sars had it near Flemish Cap, east of the Grand Banks. Wolfenden 

 (1911) has described as this species a Gaidius from the Antarctic and off the Cape of 

 Good Hope, but differences which he mentions, though slight, may prove sufficient to 

 differentiate the northern from the southern form when larger series are compared; 

 hence the bi-polarity of the species can not be accepted yet as definitely established 

 (With, 1915). G. tenuispinis has not been found in the Pacific, where a closely allied 

 form, G. pungens (Giesbrecht), occurs in lower latitudes. 



There are no previous records of G. tenuispinis in the Gulf of Maine or farther 

 south in the western Atlantic, but odd specimens were taken in the vertical hauls 

 off Penobscot Bay on April 10, 1920 (station 20097), and again on January 1, 1921 

 (station 10496) — about 6 specimens on the first occasion and 15 on the second. It 

 also figures (1 per cent) in the list of copepods taken at the outermost station outside 

 the continental edge off Shelburne, Nova Scotia, on March 19, 1920 (station 20077, 

 table, p. 300) . Evidently G. tenuispinis reaches the gulf, which is its extreme southern 

 limit on the American coast, only as an accidental stray from the north, and is more 

 apt to do so during the cold half of the year than in summer. 



Halitlialestris croni (Kr0yer) 



This is one of the largest of harpacticoid copepods and one of the few represent- 

 atives of the group recognized in the plankton of the open Gulf of Maine by Doctor 

 Esterly (in Bigelow, 1914, p. 115; 1915, p. 287; 1917, p. 290) or by Dr. C. B. Wilson 

 (tables, p. 207), and at Woods Hole by Fish (1925, p. 146). Itis widely distributed in the 

 North Atlantic, being known on the European side from the Bay of Biscay northward 

 to the Faroe Channel, Iceland, Spitzbergen, and north of Norway, including the 

 English Channel and the northern part of the North Sea. On the American side it has 

 been reported at several stations in the Gulf of St. Lawrence (Herdman, Thompson, 

 and Scott, 1898; Willey, 1919), in the Straits of Belle Isle (Herdman, Thompson, and 

 Scott, 1898), in the Gulf of Maine, and at Woods Hole, but as yet not farther south. 



Gulf of Maine. — Previous records for the Gulf are two hauls in the central basin 

 in July, 1894 ; 34 St. Andrews, September, 1915 (Willey, 1919) ; and occasional specimens 

 mentioned for that locality during the months of November, January, and April in 

 Doctor McMurrich's lists of the local plankton (p. 12). H. croni was not detected in 

 the numerous horizontal hauls for the years 1912 to 1914, reported on by Doctor 

 Esterly, probably because entirely overshadowed by the masses of Calanus and other 

 calanoids; but the vertical and surface hauls for 1915, 1920, and 1921 (tables, pp.297, 

 299 and 304) extend its range over the Gulf of Maine generally, including the coastal zone 

 and the basin indifferently, to the eastern part of Georges Bank and to the continental 

 slope off its southwestern face (fig. 74). It has not yet been found on the western 

 part of the bank or off Nantucket, but judging from its widespread distribution in the 

 gulf it is to be expected there. The records cover the months of March, April, May, 

 June, August, September, and January, proving that it is present in the gulf the year 



»< Listed by Sharpe (1911) from latitude 42° 55', longitude 68° 49', and latitude 42° 07', longitude 70° OS', and collected by the 

 Grampus. 



75898—26 16 



