PLANKTON OF THE GULF OF MAINE 363 



(Nova Scotia), about Eastport, in Passamaquoddy Bay, at Grand Manan, about 

 Mount Desert Island, in Penobscot Bay, in Boothbay Harbor, at the mouth of the 

 Kennebec River, in Casco Bay, near Cape Porpoise, in Kittery Harbor, about the 

 Isles of Shoals, in Gloucester Harbor, at many localities and on many occasions in 

 Massachusetts Bay, and off Cape Cod, while I have no doubt that Aurelia may be 

 found in season in every bay, harbor, or river mouth and all along the coast line from 

 Cape Cod to Cape Sable. The localities marked on the accompanying chart fail to do 

 justice to the universal distribution of Aurelia in the coastwise waters of the Gulf 

 because most of our cruises and towings have been carried on outside the outer islands 

 and headlands, whereas Aurelia is most plentiful and appears most regularly in more 

 or less inclosed estuarine waters and bays. 



Although Aurelia is so universally plentiful along the coast line of the gulf, it 

 seldom strays more than a few miles offshore. We have only two records of it more 

 than 15 miles from the nearest land, and only one more than a mile or two outside the 

 100-meter contour (fig. 100). * Thus its distribution is more strictly coastwise than 

 that of the red jellyfish (Cyanea, p. 357). 



The lack of locality records off western Nova Scotia is not due to any local scarcity 

 of Aurelia (for I have seen it in abundance in Yarmouth Harbor in August) but 

 merely reflects the fact that we have occupied no towing stations close in to this part 

 of the coast during its annual season of plenty. 



To emphasize more strongly how closely Aurelia is bound to the coast in the 

 Gulf of Maine, I need only add that whereas it was frequently seen floating on the 

 surface or taken in our tow nets during July and August of 1912, when we did much 

 of our cruising close in along the shore, we saw very few in the open guff (all of them 

 near land) in July or August, 1913, when we worked mostly outside the 100-meter 

 contour. We had only one specimen during our summer cruise of 1914, when the 

 stations were located well out in the gulf, though Aurelia was plentiful enough 

 during both these summers in bays and harbors. We have not found it on Georges 

 Bank or on Browns Bank, nor has it been recorded from either, though the former 

 is an important center of production for Cyanea (p. 359). Neither is there any 

 record of Aurelia over Nantucket Shoals, although the proximity of Nantucket 

 Island suggests that it will be found there. 



The facts of distribution just outlined make it certain that in the Guff of Maine 

 the attached stage of Aurelia is invariably passed in very shallow water, probably 

 never deeper than 20 meters or so. In fact, many of its planulse are set free along 

 the tide mark where their parents are cast ashore by the autumn gales. For this 

 reason as well as because of its large size this medusa is perhaps the most trust- 

 worthy indicator of coast water in the Gulf of Maine. 



Thanks to the definite seasonal periodicity of its occurrence and to the ease 

 with which its early stages may be raised in aquaria, the life history of Aurelia is 

 well known; in fact time has added little but corroboration to Louis Agassiz's (1860 

 and 1862) account, apart from the details of egg cleavage, histology, etc., which 

 need not concern us here. The course of its life is, briefly, as follows: 5 



> For the offshore records, see Bigelow, 1914, p. 124; 1915, p. 316; 1917, p. 303. 



' Mayer (1910, p. 626) gives an excellent account of the development of Aurelia and of the different ways in which the formation 

 of the gastrula has been described. 



