Fishes of the Western North Atlantic 383 



their anterior and posterior margins nearly straiglit, inner margin weakly convex; 

 outer corners abrupt, and posterior corners a little more broadly rounded; length of 

 anterior margin about as great as distance from its own origin to inner rear corner. 

 Claspers of mature males with simple tips, reaching rearward nearly to origin of tail 

 spine. 



Color. Very young specimens described ^^^ as yellowish or light brown above; 

 adults grayish-, olivaceous- or reddish-brown or dusky green above, sometimes with 

 bluish spots of various shapes; often darker near outer and posterior margins; sometimes 

 narrowly edged with white; terminal part of tail and upper tailfold dusky or black. 

 Lower surface whitish or pure white, sometimes with irregular dark blotches on tail 

 and disc or with pectorals and pelvics irregularly margined with dusky in large spe- 

 cimens."" 



Relationship to Eastern Atlantic Species. Among the five species of Dasyatis of the 

 eastern Atlantic, D. say is rather sharply separated from D. margarita, D. pastinaca, D. 

 rudis, and D. violacea by the anterior contour of its disc and by its much wider upper 

 tailfold; from D. aspera by the same features that separate it from D. centroura (p. 380). 



Size. Large specimens in French Guiana are described as averaging about one 

 meter in width, which seemingly is close to the maximum, 36 inches being the greatest 

 breadth recorded for any North American specimen. A male with large claspers in our 

 Study Material is 24 1/2 inches wide, and the smallest female so far recorded as con- 

 taining eggs or as having a dilated uterus was 13 inches wide."i A female 27 inches 

 wide from the Virginia Coast weighed 35 pounds. '^^ 



Developmental Stages. Only the left-hand ovary and uterus have been found func- 

 tional in the majority of gravid females examined, though both uteri have been found 

 to contain embryos in occasional specimens ;i^* in fact, it appears to be the general rule 

 among Sting Rays that only one of the two ovaries and uteri function at a time. As 

 the eggs ripen, the uterus enlarges and its wall becomes covered with slender red villi 

 about two cm long and slightly enlarged at their tips. During later development the 

 embryos lie bathed in a creamy yellow fluid which is probably secreted by the villi 

 and which seemingly provides nourishment to the embryo in addition to that provided 

 from the yolk sac, for the large intestine of larger embryos has been found filled with 

 a similar substance. It has been suggested that this so-called "milk" is absorbed at 

 first through the gill filaments and later through the spiracles. But no exact observa- 

 tions have been made, nor is it known at what stage in development the mouth becomes 

 functional. The period of gestation is not known, but eggs 12—15 "^"^ i" diameter have 

 been found in a female which at the same time had embryos of the next older generation 

 nearly ready for birth. Females have been found to contain two, three or four embryos; 

 in one case three males and one female. Gravid females with embryos nearly ready for 



129. We have no color notes from life. 



130. The largest of both sexes that we have seen show this dark edging below. 



131. Gudger, Proc. biol. Soc. Wash., 2$, 1912: 146. 132. Hamilton and Smith, Copeia, 1941: 175. 

 133. This account of the uterus and of its contents is adapted from observations by Gudger (Proc. biol. Soc. Wash., 



2$, 1912: 144; 26, 1913: 99). 



