PLANKTON OF THE GULF OF MAINE 



17J 



Eurytemora hcrdmani. 

 Gaidius tenuispinis. 

 Halithalestris croni. 

 *Harpacticus litoralis. 

 *IIarpaeticus uniremis. 

 Heterorhabdus spiuifrons. 

 *Idya furcata. 

 Labidocera sestiva. 

 Lucicutia grandis. 

 Metis iguea. 

 Mecynocera clausi. 

 Metridia longa. 

 Metridia lucens. 

 Monstrilla serricornis. 



Oithona similis. 

 *Parathalestris japkeoni. 

 Phyllopus bidentatus. 

 Pleuromamma (genus). 

 Pseudocalanus elongatus. 

 Rhincalanus cornutus. 

 Rhincalanus nasutus. 

 Scolecithricella minor. 

 Temora longicornis. 

 Tortanus discaudatus. 

 Undeuchaeta major. 

 Undeuchaeta minor. 

 *Zaus abbreviatus. 

 *Zaus spinatus. 



Acartia clausi Giesbreclit 



This species has a more southerly distribution than A. longirernis, ranging widely 

 on both sides of the temperate North Atlantic, southward from western Norway on 

 the one side and from the St. Lawrence River on the other; but it was not found in 

 any of the samples of Arctic plankton examined by Sars (1900) and at only one station 

 north of the Arctic Circle in the collection of the Canadian Arctic expedition (Willey, 

 1920). In general, it may be described as neritic, as opposed to oceanic, for although 

 it is widely distributed in the oceanic areas of the North Atlantic, European students 

 have found it most plentiful in coastal waters such as the Irish and English Channels 

 and the southern parts of the North Sea. It is found plentifully in water as little 

 saline as 18.42 per mille, but salinities much lower than this apparently bar it (Farran, 

 1910). Willey (1920) has characterized it as more of an estuarine form than A. 

 longirernis, but the distribution outlined below for the Gulf of Maine shows that this 

 can hardly be laid down as a general rule. Steuer (1923) has recently charted its 

 distribution in the Eastern Atlantic and generally. 



In a continuous collection of plankton from Liverpool to Quebec, made by Sir 

 Wm. Herdman in 1897, it disappeared at longitude 38° 6' W. and did not reappear 

 until the ship was well up the St. Lawrence River (Herdman, Thompson, and Scott, 

 1898). T. Scott (1905) reports it from the Gulf of St. Lawrence, but Willey (1919) 

 did not find it among the many samples which he reported on thence, and if not 

 wholly wanting it is at least so rare over the continental shelf off Nova Scotia and 

 south of Newfoundland that the Canadian fisheries expedition took it at only one 

 station — this, curiously enough, the outermost on the line off Cape Sable (Willey, 

 1919). 



It was not detected among the collections made by the Gram-pus between Cape 

 Cod and Chesapeake Bay in 1913 or in 1916, though its relative A. tonsa swarmed 

 locally off Delaware Bay during August of the latter year (Bigelow, 1922, p. 146). 

 Neither did Wheeler (1901) nor Sharpe (1911) find it at Woods Hole, where A. tonsa 

 is one of the commonest of copepods. It is not uncommon there during some winters, 

 for Fish (1925, fig. 46) found it regularly from October, 1922, to February, 1923. 

 It does not appear in Fowler's (1912) list of Rhode Island copepods, but Williams 

 (1906 and 1907) describes it as abundant in Narragansett Bay in January and 



