Fis/ies of the Western N^orth Atlantic 349 



and about equal to distance between inner ends of first gill openings. Eye about 75- 

 85 7o ^s long as distance between eyes and about equal to length of spiracle. Distance 

 between inner ends of first gills about 1.7— 1.9 times as long as distance between ex- 

 posed nostrils; distance between inner ends of fifth gills about 62 "/o ^s great as that 

 between inner ends of first gills. Free posterior margin of nasal curtain weakly con- 

 cave, fringed, the individual lobes simple or variously divided, those of the two sides 

 separated in midline by a narrow gap. Mouth with upper jaw moderately projecting 

 centrally and lower jaw moderately recessed, a little more so on mature males than on 

 females. Floor of mouth, centrally, with a transverse series of three stout papillae, 

 sometimes with another more slender papilla on one side or on both sides. 



Teeth 3' to 5*,^* about equally large all along each tooth band except for some- 

 what smaller ones near outer corners; those of females and immature males tetragonal 

 with rounded corners, a little broader (transversely) than long (anteroposteriorly), the 

 functional surfaces weakly rounded or flat, often scored ; those of sexually mature males 

 with low conical cusp; 6—8 rows in function simultaneously in upper jaw and about 

 12 rows in lower jaw near center but only 8—9 rows near outer corners. 



Anterior margins of pelvics nearly straight on small specimens, usually more 

 convex on larger; outer corners moderately rounded, the posterior corners usually 

 more broadly rounded but varying widely in degree of curvature among large spe- 

 cimens; anterior margin of pelvic about as long as distance from its own origin to rear 

 tip of longest ray of pelvic. 



Color.*^ Upper surface of disc gray, dark or olivaceaous brown, or olive green, 

 depending on the color of the bottom on which the Ray is lying; sometimes darker 

 toward outer margins and narrowly edged with white; a gray or whitish spot on median 

 line of snout close in front of eyes; sides of anterior part of tail grayish or whitish, its 

 dorsal keel, ventral fold, and terminal portion black or brownish black. Lower surface 

 of disc white or whitish with an edging of gray or brown, either solid or broken into 

 irregular spots; inner posterior portions of pelvics so marked also. Tail spine described 

 as dark on fresh specimens. 



Size. Embryos nearly ready for birth are about 126 (see Study Material) to 170— 

 180 mm broad, suggesting a width not far from 200 mm as usual at birth. It is probable 

 that females may mature at a breadth of 750—800 mm, possibly smaller, for a North 

 Carolina specimen 828 mm wide (33 in.) gave birth to three young on capture. Males 

 may mature at a somewhat smaller size, for one about 510 mm wide (20 in.) has been 

 reported as adult ; furthermore, the claspers of another of about that same size are so 

 large as to suggest the imminence of sexual activity. The largest specimens of D. ameri- 

 cana positively recorded have been: 40, 42, 44, and 60 inches in width, all of these 

 recently examined by us at Bimini, Bahamas. One about 37 inches wide from the 

 Tortugas, Florida weighed 58 pounds. =" 



48. The smallest specimen which we counted, with disc 14 inches wide, had 39 series in each jaw; the largest, 60 inches 



wide, had 56. 

 4.Q. We have no color notes from life. 50. Gudger, Aust. Mus. Mag., 6 (6), 1937: 208. 



