358 BULLETIN OF THE BUREAU OF FISHERIES 



medusae in the act of releasing their ova are taken in abundance from the early part 

 of June (McMurrich, 1891) until September (Sumner, Osburne, and Cole, 1913a, 

 p. 575). 



North of Cape Cod it seems that the ephyras of Cyanea are liberated later in 

 the season, corresponding to the more tardy vernal warming of the water. I 

 have no direct data as to the precise season when the ephyrae are set free in the 

 Gulf of Maine, 98 for we have never seen a young Cyanea in the inner parts of the 

 gulf during the spring months, but the few we have taken there during the last half 

 of June have been only 2 to 3 inches broad (e. g., north of Georges Bank, June 25, 

 1915, station 10298). It is not until the first part of July that we have seen Cyanea 

 as large as 6 to 10 inches in diameter in the Massachusetts Bay region, pointing to 

 April and May as the season when their liberation commences. At that time the 

 smallest medusas of Cyanea must be extremely plentiful along the shores of the gulf. 

 Alexander Agassiz (1S65, p. 45) saw great numbers of them measuring J^ to 3 inches 

 in diameter on the surface in Provincetown Harbor in the early morning, all, however, 

 sinking as the sun rose, and we have found them in abundance on Nantucket Shoals 

 in April (p. 359). Our failure to take them in our tow nets elsewhere in the gulf 

 during those months, in spite of the considerable number of hauls, recalls Louis 

 Agassiz's remark (1862, p. 109) that "there must be something peculiar in the habits 

 of the young Cyanea to render them apparently so rare, when in the adult state they 

 are so common" along the coasts of Massachusetts Bay. His suggestion that they 

 keep near the bottom during their early stages has been corroborated by Mayer's 

 (1910, p. 600) observation that young Cyaneas rarely come to the surface in the 

 aquarium but spend most of their time clinging to the bottom or side of the tank 

 with their widespread oral fringes. The tendency of the small Cyaneas to seek the 

 surface so much more regularly about Woods Hole than in the Gulf of Maine is an 

 interesting local difference in habits still awaiting explanation. 



It seems that Massachusetts Bay and the Gulf of Maine generally offer an 

 especially favorable environment for the Cyaneas, which grow so rapidly there that 

 many of them attain a diameter of 2 to 4 feet by the close of the summer. This is 

 about the average size at the end of their lives, though Alexander Agassiz (1865, p. 44) 

 records one monster from Massachusetts Bay that measured lYi feet across the disk, 

 with tentacles upward of 120 feet in length. 



It is certain that the breeding season for Cyanea endures from June until mid- 

 autumn in the Gulf of Maine, for on the one hand Hyde (1894) obtained developing 

 eggs near Cape Ann early in summer, while on the other we have frequently found 

 the medusas, with mature eggs and carrying great numbers of the planulas, cast up 

 on the beach in September and early October. Probably Cyanea becomes sexually 

 mature as soon as a certain size is attained, regardless of the precise season when 

 this takes place, and continues to produce eggs or sperm throughout the remainder 

 of its life, with the autumnal storms, which either cast the medusas on the shore or 

 batter them to pieces at sea, setting the natural period to their existence. We find 

 no record of Cyanea in the Gulf of Maine after October. 



•» One ephyra was taken near Mount Desert on June 14, 1915, but it was probably among the latest produced there. 



