384 Memoir Sears Foundation for Marine Research 



birth have been reported only during the warm season in the northern sector of its range 

 (North Carolina and Virginia). But it is likely that young are produced at all times of 

 the year in subtropical-tropical latitudes. 



Young, born prematurely, as often happens when gravid females are caught, 

 "moved around rather freely but had difficulty in staying right side up . . . One, how- 

 ever, when placed in the normal position on the bottom of the aquarium, showed, in 

 the lifting of the body and In the motion of the hinder edges of the pectorals, the 

 characteristic breathing movements of the adult. "1^* The fact that a young specimen, 

 only 6.75 inches wide, lashed violently with its tail when handled, is evidence that this 

 protective act is instinctive from birth. 



Embryos nearly ready for birth are described as about 5.0—6.25 inches wide, 

 suggesting that the young are born when they are about 6—7 inches wide. And "it 

 would seem that the larger the mother the larger the young to which she gives birth. "i^^ 

 Of five specimens, 147— 161 mm broad (5 ^/4— 6 ^/g in.), in the collection of the Harvard 

 Museum of Comparative Zoology, one had a small unhealed umbilical scar, one had a 

 healed scar, and three had small yolk stalks. All of these were evidently ready for birth 

 or were newborn. 



The upper and lower tailfolds are described as already well developed even before 

 birth, "^ hence identification of even the smallest free-living specimens is easy. 



Habits. Dasyatis say, like other Sting Rays, spends most of its time lying on bottom, 

 usually partially buried in sand or mud, with only the eyes and the spiracles exposed, 

 and it is so motionless that it is apt to escape notice unless disturbed. In situations 

 where the flats over which they feed are laid bare at ebb tide, as along the North 

 Carolina Coast, they move in and out with the rise and fall of the water. They are much 

 more active on occasion than might be expected from their sedentary habits, for in- 

 dividuals that take part in the summer migration northward along the United States 

 Coast (p. 385) carry out journeys of some hundreds of miles. When on the move, they 

 often break the surface with rapid splashes of the pectorals, first flapping rapidly ahead 

 for a short distance and then slackening to settle down again out of sight; sometimes 

 their tails lash out above the water, a procedure that makes them conspicuous on their 

 arrival in the bays and inlets along the Middle Atlantic Coast of the United States."' 



Throughout its range D. say is much more plentiful in water of only a few inches 

 down to 8 or 10 feet than in water deeper than that. We have seen them taken from 

 pound nets in a depth of about 30 feet in lower Chesapeake Bay but, other than this, 

 20 feet 13^ is the greatest depth from which they have been actually recorded. For such 

 of the stock as takes part, the yearly migration northward to the Middle Atlantic Coast 

 of the United States entails the crossing of considerably deeper waters, and it may 

 prove that the regular range of D. say off open beaches extends deeper than is re- 

 cognized at present. 



134. Gudger, Proc. biol. Soc. Wash., 25, 1912: 144. 135. Gudger, Proc. biol. Soc. Wash., 25, 1912: 145. 



136. Hamilton and Smith, Copeia, 1941: 175. 



137. For a vivid account, see Hamilton and Smith (Copeia, 1941: 17?). 



138. Hamilton and Smith, Copeia, 1941: 175. 



