3 8 Memoir Sears Foundation for Marine Research 



between base of saw and its tip; length of longest tooth a little more than half as great 

 as distance between nostrils ; anterior margins of saw teeth sharp, but posterior margins 

 flattened transversely even on very small specimens; teeth longitudinally channeled 

 posteriorly on larger specimens; their anterior outlines weakly convex, their tips sharp 

 on young specimens but more or less blunted on large; basal pair of teeth separated 

 from apparent level of emergence of saw by a distance a little greater than length 

 of orbit. 



Head from origin of saw to level of first gill openings about 7* of trunk from 

 base of saw to origin of caudal ; dorsal profile about as convex as in P. pectinatus, but 

 lateral outlines narrowing more abruptly to base of saw (cf. Fig. 6 E with 4 F). Orbit 

 about as long as spiracle; distance from anterior margins of orbits to base of saw, and 

 length from mouth to base of saw, a little greater than width of mouth. Spiracles about 

 0.8 as long as nostril. Gill openings with anterior outlines strongly convex; distance be- 

 tween inner ends of fifth pair about equal to distance from mouth to base of saw. Nostrils 

 with anterior margin expanded as a digitate lobe with rounded tip, extending rearward 

 across nasal opening, the posterior margin following a continuous arc (bilobed in 

 P. pectinatus, Fig. 4F). Mouth transverse, nearly straight, with irregular folds at corners, 

 its breadth about 2.4 times as great as distance between nostrils. 



Teeth increasing in number of series from about ^ on newborn specimens to 

 about 1^5^ at a length of 1,300 to 1,400 mm, and perhaps more on larger individuals; 

 dome-shaped anteriorly, with obtuse cutting edge, relatively somewhat larger than in 

 P. pectinatus, and with bases extending farther posteriorly; rather loosely set in quin- 

 cunx; the oral bands as in P. pectinatus, with about 12 rows in function simultaneously 

 in each jaw. 



The two dorsals of similar shape, with deeply concave posterior margins (much 

 more so than in P.pectinatus)\ free lower margins less than half (about 40 %) as long 

 as bases; apices narrowly rounded, their free rear tips subangular but blunted; anterior 

 2/3 of base of first dorsal anterior to origin of pelvics, its origin opposite or a little 

 anterior to level of rear corners of pectorals; base of second dorsal about 80 "/g as long 

 as base of first dorsal. Interspace between first and second dorsals about 1.6 times as 

 long as base of first dorsal. Interspace between second dorsal and caudal nearly or quite 

 as long as base of second dorsal. Caudal subtriangular, with narrowly rounded corners, 

 the lower expanded to form a low but definite lobe; upper margin nearly straight or 

 weakly convex and nearly as long as distance from origin of second dorsal to origin 

 of first dorsal (thus considerably longer relatively than in P. pectinatus)\ lower anterior 

 margin weakly convex and about half as long as the upper; the caudal relatively nar- 

 rower than in P. pectinatus^ its vertical height at level of lower corner only about half 

 as great as length of upper margin. Caudal axis only slightly raised. Pelvics about as 

 long from origin to tip as interspace between first and second dorsals; their shapes as 

 in P. pectinatus, except with distal margins weakly concave. 



Color. Upper surface of trunk of salt-water specimens, when fresh-caught, either 

 dark gray or golden brown, the base of the saw also golden brown in some cases. A 



