2 02 Memoir Sears Foundation for Marine Research 



long, from Lat. 36°46' N, Long. 74°4i' W (Harv. Mus. Comp. Zool., No. 34762). 

 Female, 401 mm, from 70 miles SSW of Montauk Point, Long Island, New York 

 (Harv. Mus. Comp. Zool., No. 36315). 



Disc: extreme breadth 55.3, 54-6; length 44.2, 44.0. 



Snout length: in front of orbits 9.5, 9.0; in front of mouth 10.3, ii.o. 



Orbits: horizontal diameter 3.6, 4.2; distance between 3.3, 3.6. 



Spiracles: length 2.9, 3.2; distance between 6.0, 6.2. 



Mouth: breadth 5.9, 5.7. 



Nostrils: distance between inner ends 6.3, 6.0. 



Gill openings: lengths, ist 1.8, 2.1 ; 3rd 1.8, 2.1 ; 5th i.o, 1.7; distance between 

 inner ends, ist 12.3, 13.0; 5th 5.4, 7.2. 



First dorsal fin: vertical height 2.9, 1.7; length of base 6.0, 5.1. 



Second dorsal fin: vertical height 2.4, 1.5; length of base 6.1, 4.9. 



Pelvics: anterior margin 11.3, 11.2. 



Distance: from tip of snout to center of cloaca 40.5, 40.7 ; from center of cloaca 

 to 1st dorsal 43.0, 45.7; to tip of tail 59.5, 59-3; from rear end of 2nd 

 dorsal base to tip of caudal 2,-S^ 3-°- 



Interspace between: ist and 2nd dorsals 0.9, 0.8. 



Disc 1.2 — 1.3 times as broad as long, noticeably obtuse in front, the maximum 

 anterior angle in front of spiracles about 112—115° ^" mature specimens; anterior 

 margins weakly concave just posterior to tip of snout and again opposite spiracles; 

 otherwise rather strongly convex, the contour about the same in males as in females; 

 outer corners broadly rounded, posterior corners less so; posterior margins strongly 

 and evenly convex. Axis of greatest breadth about 70 "/o of distance back from tip of 

 snout toward axils of pectorals. Tail with narrow dermal folds along posterior 2/3 to 

 Vs; its length from center of cloaca to origin of first dorsal about 1.2 times as great as, 

 to tip of tail about 1.5 times as great as, distance from snout to cloaca both in adults 

 and in young after loss of filamentous prolongation. 



Smallest specimens (85—125 mm long) with a few small thorns on rostral ridge; 

 three larger ones in front of each orbit, a few along inner margin of orbit, and 2—3 

 close behind latter; 1—3 on each shoulder; a row of about 33—35 thorns along midline 

 of disc and tail to first dorsal, and 1—2 thorns between first and second dorsals. Larger 

 specimens have a row of thorns along each margin of the rostral cartilage (none on tip 

 of snout), 2—5 in the space between the orbits, a row around the inner margin of the 

 orbit, several in front of it and 1-3 behind, a patch of about 3—6 thorns on each 

 shoulder, 1—3 irregular rows along the midbelt of back and tail on either side, but 

 the median row is partially lost with growth in some cases. On small specimens the 

 upper surface of the disc and tail is largely prickly in addition to the thorns, but on 

 large ones the upper surface is naked apart from the thorns except for a prickly patch 

 that persists beside each eye and sometimes a few prickles on the outer parts of the 

 pectorals. Pelvics prickly in young; posterior parts of pelvics also prickly in females 



