3 04 Memoir Sears Foundation for Marine Research 



to ist dorsal 54.8, 51.5; to tip of tail 67.1, 64.5; from rear end of 2nd 

 dorsal base to tip of caudal — , 4.1. 

 Inters-pace between: ist and 2nd dorsals 0.9, 0.6. 



Disc about i.i — 1.2 times as broad as long; snout angular, blunted at tip; maximum 

 anterior angle in front of spiracles about 100—110°; anterior margins nearly straight 

 anterior to level of orbits, weakly convex thence outward on females but rather conspi- 

 cuously concave at general level of spiracles on mature males, and tip of snout more 

 prominent; outer and posterior corners broadly rounded; posterior margin evenly and 

 rather strongly convex and inner margin weakly convex to axil. Axis of greatest breadth 

 about 72 "/o of distance rearward from snout toward axils of pectorals. Tail from center 

 of cloaca to first dorsal about 1.5— 1.7 times as long as distance from center of cloaca 

 to snout and about twice as long to tip; its lateral folds narrow, extending entire length 

 from close posterior to tips of pelvics and widening a little rearward. 



Upper surface of disc roughened with small, sharp, movable spines except on pos- 

 terior margins and along mid-dorsal belt, most of them covered with skin ; skin above 

 eyes finely prickly; two small thorns over tip of rostral cartilage on youngest, three 

 small and one large on half-grown specimens; none on tip on adults, but there is a 

 cluster a little rearward; about 7—1 1 of various sizes around inner margin of orbit on 

 adults, either in continuous row or interrupted midway; one large thorn inward from 

 inner end of spiracle; a patch of 8 — 12 scattered outward from each eye on half-grown 

 specimens, increasing in number and size and spreading by maturity over the marginal 

 belt as a whole anterior to level of spiracles; at first two, later 3—5, large thorns on each 

 shoulder; midline of back with a continuous row of 1 1— 14 thorns from nuchal region 

 to pelvic girdle, larger ones alternating with smaller at first but later all about equal in 

 size, followed by about 45-50 along tail to first dorsal, decreasing in size rearward 

 and in regularity of arrangement ;i*' the midrow flanked on either side by one irregular 

 additional row from a little behind pectoral girdle to base of tail and by 1—2 such rows 

 thence rearward past dorsals; central and posterior parts of pelvics with a few small 

 prickles, also upper parts of dorsals; caudal membrane smooth. Mature males with 

 thorns of mid-dorsal belt of disc somewhat fewer, smaller, and in less regular linear 

 arrangement than on females; also outer corners of pectorals strewn with small thorns 

 which are not present on females; alar spines about 12-20, directed rearward-inward, 

 irregularly arranged, not conspicuous. Lower surface smooth except sometimes a few 

 small spinelets along outer edges of tail close behind tips of pelvics, and a few small 

 scattered prickles along its anterior one-sixth. 



Snout in front of orbits about 2.6 times as long as orbit, its length in front of 

 mouth about 2.1 times as great as distance between exposed nostrils. Orbit about 1.3 

 times as long as distance between orbits and about 1.6 times as long as spiracle. Dis- 

 tance between first gill openings 2.1—2.4 tinges as long as distance between exposed 

 nostrils, 1.3— 1.4 times between fifth gill openings; first gill openings 1. 1—2.0 times as 



10. Counting is difficult along the tail. 



