358 Memoir Sears Foundation for Marine Research 



pounds at 38-40 inches; 130-150 pounds at 46—50 inches; and 155 pounds at 52 

 inches." Another 52 inches broad weighed 180 pounds,'* and a weight of 350 pounds, 

 reported for one seven feet wide, may not have been exaggerated. Different individuals 

 of a given size may vary by nearly 100 "/o in weight in extreme cases. The relationship 

 between size and weight is about the same for the one sex as for the other before they 

 become sexually mature; but it is likely that gravid females may be heavier than males 

 of equal size. 



Developmental Stages. Embryos of this Ray have not been studied as yet, nor is 

 the number in a brood known. ^^ 



Habits. Nothing is known of the way of life of D. centroura to differentiate it from 

 other Sting Rays. Probably it subsists chiefly on whatever large crustaceans and hard- 

 shelled mollusks are most readily available locally. The stomachs of specimens taken 

 near Woods Hole have contained large numbers of crabs (Cancer), clams {Mya\ and 

 large gastropods (Lunatia, equals Polinices), as well as squid (^Loligd) and annelid worms ; 

 one contained fragments of a small fish. It bites readily on bait of crabs, clams, or fish. 



Its breeding habits are yet to be learned, as is the season at which it produces 

 its young. ^1 



Z). centroura is known only as a warm-season visitor to coastal waters. In the 

 vicinity of New York it appears in June, earlier or later in different years.*- Thereafter 

 it is encountered in New Jersey, New York and Rhode Island waters through July, 

 August, and September,*^ occasionally in the first week of October. Apparently it 

 appears equally early in the season as far east as southern Massachusetts, having been 

 reported repeatedly in the vicinity of Woods Hole in June. But available information 

 suggests that its autumnal withdrawal thence takes place several weeks earlier in the 

 season than from the shores of New York and New Jersey, for the latest capture so 

 far reported at Woods Hole is August 25. It freely enters the inlets and larger bays 

 and sounds, such as Long Island Sound, Narragansett Bay, Vineyard Sound, and Buz- 

 zards Bay, and it has been reported repeatedly in more nearly estuarine situations, such 

 as Sandy Hook Bay and Great Egg Harbor on the coast of New Jersey. It has never 

 been reported from brackish or fresh waters. Although it is sometimes seined in the 

 surf, it seems to remain more commonly in water as deep as that fished by the pound 

 nets (30 ft. or so at high tide), for we find no report of a bather wounded by one. On 



78. Based on 28 specimens weighed at Woods Hole during the summer of 1946. 



79. Breder, Copeia, 166, 1928: 6. 



80. Broods of four and five have been reported by Moore (Bull. U. S. Fish Comm., 12, 1894: 358) as born in an aquarium, 

 but it seems almost certain that they were of some other species, for the mothers were described as only two feet 

 wide, a size much smaller than that at which D. centroura matures. 



81. An earlier statement (Moore, Bull. U. S. Fish Comm., 12, 1894: 358) that adult D. centroura desert the bays of 

 New Jersey after bringing forth their young and that all taken there after August 20 were young of the year seems 

 to have referred to some other and smaller Ray, for the breadth of females that produced young in the aquarium 

 was given as only two feet. 



82. The earliest recorded date with which we are acquainted is June 3 for Orient at the eastern end of Long Island, 

 New York. 



83. Daniel Merriman and Yngve H. Olsen advise us that an immature female, 58 inches long to end of tail, weighing 

 241/2 pounds, was trawled September 25, 1950, 5 miles SSE of Watch Hill, Rhode Island. 



