Fishes of the Western North Atlantic 283 



also two rather regular rows of thorns a little larger than those of the median row"* 

 on each side of tail and extending nearly to tip; 9—10 thorns around orbit, and a patch 

 of smaller thorns inward from spiracle. Tip of snout and rostral ridge, space between 

 spiracles, midbelt of disc back to pelvic girdle, and outer margins abreast of eyes 

 (smooth on small specimens) developing a few scattered prickles with growth. Maturing 

 males developing 12—13 large thorns near margins of disc opposite eyes but losing the 

 prickles from midbelt of disc. Alar spines of mature males in several irregular rows, 

 covering a roughly triangular area that extends forward along margins of pectorals past 

 level of posterior edges of spiracles, the innermost row longest. Lower surface entirely 

 smooth on small specimens; prickles, interspersed with small thorns, developing on 

 tip of snout with growth; also, prickles developing along outer anterior margins of 

 disc finally roughen entire lower surface of head rearward to about the mouth on males 

 and along the median belt about as far as fifth gill openings in females; lower side of 

 extremity of tail prickly on females but smooth on males. 



Snout in front of orbits about 3.3—4.0 times as long as orbit in young of both 

 sexes and in males to maturity, about 4.5—5.0 times in mature females; its length in 

 front of mouth about 1.6— 1.8 times as long as distance between nostrils in young and 

 in mature males, about 2.0—2.2 times in large females. Distance between first gill 

 openings 1.8—2.0 times as long as distance between exposed nostrils, about equal 

 between fifth gill openings; first gill openings i. 0—1.2 times as long as fifth and about 

 16-27 "/o as long as breadth of mouth. Nasal curtain and expanded posterior (outer) 

 margin of nostril each with shallow fringe. Mouth nearly straight in females, lower 

 jaw a little more arched in mature males. 



Teeth |^8' those of small and half-grown specimens close-set in quincunx, with 

 nearly circular base and stout conical cusp on all except those of the oldest row; those 

 of adults of both sexes spaced more loosely in transverse series with well developed 

 cusp; uppers of males a little more slender than those of females, the lowers con- 

 spicuously so. 



Dorsals similar in size and shape, posterior margin more or less re-entrant. Inter- 

 space between first and second dorsals varying from only about 30 "/o as long, to about 

 as long, as base of first dorsal. Caudal membrane posterior to second dorsal about as 

 long as base of first dorsal. Pelvics moderately concave outwardly, strongly scalloped 

 around the indentation; anterior margin about 67—72 "/o as long as distance from its 

 own origin to rear tip of pelvic; anterior lobe noticeably small but including three or 

 four slender radials besides the first stout one; posterior lobe with weakly convex 

 outer margin; rear tip broadly rounded in female but narrowly so in mature male, 

 extending back about 10—16 "/o of distance from axils of pelvics toward tip of tail in 

 young and adult female, about 20 % iri adult male. Claspers of sexually mature male 

 reaching back a little more than halfway from axils of pelvics toward first dorsal. 



Anterior rays of pectorals reaching about 51— 56*/o of distance from level of 

 fronts of orbits toward tip of snout. 



163. This contrast in size is the reverse of what is usual among Skates of the western North Atlantic. 



