342 BULLETIN OF THE BUREAU OF FISHERIES 



on Mount Desert Island; and in the bays of Grand Manan, where Fewkes found 

 it one of the commonest medusae in the summer of 1S86 and I, myself, in August, 

 1910. Its breeding period endures from mid-July throughout August or even later, 

 both in Massachusetts Bay and in Penobscot Bay, hence is no doubt uniform along 

 the whole coast line of the gulf. The eggs are shed freely, are easily fertilized 

 artificially, and the early stages in development can be followed without difficulty. 



I have not seen Melicertum after August, but A. Agassiz (1865, p. 181) 

 describes it as plentiful in Massachusetts Bay "in the fall at the time of spawning." 

 How late in the season its medusas may survive is not known. Perhaps it appears 

 and dies earlier in the southwestern than in the northeastern part of the gulf, like 

 Staurophora. 



It is probable that the hydroid stage of Melicertum is invariably passed in the 

 immediate neighborhood of the coast, there being no evidence that this ever takes 

 place on Georges or Browns Banks or even on offshore ledges within the gulf, such 

 as Cashes and Platts. And whde the adult medusas occasionally drift out to sea 

 (for we have taken odd specimens over the western basin on August 9, 1913 (station 

 10088) and near Mount Desert Rock (station 10248) on August 13, 1914), it is very 

 seldom that one strays beyond the 100-meter contour; nor have we ever found 

 Melicertum in numbers anywhere outside the bays, river mouths, or harbors, except 

 off Cape Cod and near Browns Bank (p. 33, footnote). 85 



Staurophora mertensii, Brandt 



This is a boreal Arctic species, circumpolar in its distribution, ranging widely 

 over the Arctic Ocean and adjacent parts of the North Atlantic, and also in the 

 North Pacific. In the eastern side it is known from many localities about Iceland, 

 from Spitzbergen, Nova Zembla, the White Sea, all along the west coast of Norway, 

 between Scotland and Iceland, and from the northern part of the North Sea. 86 In 

 the western Atlantic and its tributaries Staurophora has been recorded from the 

 west coast of Greenland, from the east coast of Newfoundland, from many localities 

 in the Gulf of Maine, as detailed below, at Woods Hole, and as far westward along 

 the south shore of New England as Newport (Mayer, 1910) and Fisher's Island 

 Sound (Verrill, 1875, p. 43). Its known range in the North Pacific area includes 

 Bering Sea, the Aleutian Islands, and the coast of Alaska on the east, and Japan on 

 the west; and if Kramp's (1919, p. 41) contention that the S . falHandica of Browne 

 (1902) from the Falkland Islands is actually S. mertensii proves correct, it is bipolar. 



This large hydromedusa is a very conspicuous member of the plankton of the 

 Gulf of Maine during its periods of plenty, for it attains a diameter of upwards of 

 200 millimeters at maturity and is made easily recognizable by its white central 

 cross. It has not been actually demonstrated that Staurophora passes through a 

 hydroid stage, but its systematic relationships and its seasonal history, outlined 

 below, make it practically certain that such is the case. 



» For locality records of Melicertum during the summer cruises of 1912 to 1914 see Bigelow, 1914, p. 125; 1915, p. 316; and 1917 

 p. 303. 



86 Kramp (1919, p. 44), who has plotted its distribution in the northeastern Atlantic, has shown that the young "Staurophora" 

 described by Hartlaub (1899) from Helgoland probably was not this genus, but that the S. discoidea described by Kishinouye 

 (1910) from Japan is not distinguishable from S. mertensii. 



