3 6 Memoir Sears Foundation for Marine Research 



Nostrils: distance between inner ends 2.4, 2.3. 



Gill openings: lengths, ist 1.5, 1.5; 3rd 1.7, 1.7; 5th i.o, 1.2; distance between 



inner ends, ist 9.4, 9.7; 5th 7.1, 7.0. 

 First dorsal fin: vertical height 7.2, 7.9; length of base 7.5, 8.0. 

 Second dorsal fin: vertical height 7.1, — ; length of base 6.0, 6.2. 

 Caudal fin: upper anterior margin 16.5, 17.6; lower anterior margin 8.3, 9.2. 

 Pe Ivies: anterior margin 6.2, 7.3. 

 Distance: from tip of snout to ist dorsal 55.3, 51.7; to pelvics 60.8, 56.7; to 



center of cloaca 63.2, 60.5; from center of cloaca to lower caudal 2 1.2, 21.8. 

 Interspace between: ist and 2nd dorsals 9.9, ii.6;2nd dorsal and caudal 5.6, 5.7. 



Trunk strongly flattened below, about 90 "/g as high as broad at origin of first 

 dorsal, narrowing rather abruptly posterior to pectorals in small specimens but only 

 gradually in larger ones, with a fleshy thickening or suppressed ridge low down along 

 either side from a little posterior to rear tips of pelvics to base of caudal. Pectorals 

 with nearly straight edges, directed outward much more abruptly from sides of head 

 than in P.pectinatus (cf. Fig. 5 with 3); anterior edge nearly straight, distal edge about 

 1. 1— 1.2 times as long as anterior edge and weakly concave; outer corners narrowly 

 rounded; posterior corners subangular. Extreme breadth across pectorals about as 

 great as distance from mouth to axils of pelvics (thus considerably greater relatively 

 than in P.pectinatus^ p. 25). Caudal peduncle at rear end of base of second dorsal 

 about 2.5 times or more as broad as thick, narrowing abruptly (as seen in dorsal view) 

 to about 1.3 times as broad as thick at origin of caudal. 



Dermal denticles more widely spaced in general over upper surface than in P.pec- 

 tinatus (cf. Fig. 6 F with 4 G) ; their blades rather strongly oblique, ovoid, with more 

 or less definite median ridge and marginal thickening toward base on either side; the 

 bases more or less definitely four-cornered, evident through the skin in very young 

 specimens but more concealed in larger. Denticles on saw rounded to oval, so closely 

 crowded as to conceal the skin entirely; those along the margins largest; those on lower 

 surface similar in form to those on upper surface, but more closely crowded. 



Saw about as long as distance from front of eye to rear corner of pectoral and 1/5 

 of total length or a little more (20-22 "/o)) thus somewhat shorter relatively than in 

 P.pectinatus;^'' its width at base about ^/g as great as its length on small specimens, 

 increasing relatively to nearly ^/g as wide as long on large; narrowing evenly forward 

 to about 0.6 as wide at tip as at base on young and to 0.4-0.5 as wide at tip as at base 

 on adults; Its tip rounded; its margin not definitely narrowed between each two suc- 

 cessive teeth. 



Saw teeth 16—19, possibly 20 (17/18 on one of our specimens, 19/19 on others 

 seen), sometimes with one more on one side than on the other, ^^ spaced only a little 

 more closely toward tip than toward base (considerably more closely toward tip In 



87. For details as to saws and saw teeth in large specimens, see Baughman (Copeia, 1943: 44). 



88. 16/17, 18/18, 18/18, 18/19, '9/19 reported in a series from Texas (Baughman, Copeia, 1943: 43). 



