3 1 8 Memoir Sears Foundation for Marine Research 



Trunk comparatively stout, about Vs as high at ist dorsal (where highest) as length 

 to origin of caudal. Caudal peduncle moderately slender, the lower as well as upper pre- 

 caudal pit strongly marked, subrectangular. Dermal ridge low but unmistakable along 

 midline of back from close behind rear end of base of ist dorsal to origin of 2nd dorsal/ 

 Dorsal profile sloping sharply, in convex contour, from ist dorsal forward. Dermal den- 

 ticles rather loosely spaced and overlapping but little, their blades nearly horizontal, about 

 as broad as long, usually with 3 low ridges, the posterior margins usually with 3 teeth, but 

 occasionally 5, the median considerably the largest; pedicel rather slender. 



Head noticeably long, forming about V3 of trunk to origin of caudal. Snout narrow, 

 ovate at tip and very long, its length in front of mouth a little more than Vs of length of 

 head, or about 1.25 times as great as breadth of mouth, and its length anterior to outer ends 

 of nostrils a little more than V2 as great as length in front of mouth. Eye nearly circular, its 

 diameter about V2 as great as distance between nostrils. Gill openings noticeably small, 

 the 1st to 3rd (slightly the longest) about as long as diameter of eye, the spaces between 

 1st and 2nd and between 2nd and 3rd of about equal breadth, but those between 3rd and 

 4th and between 4th and 5th a little narrower, the 4th gill opening over origin of pectoral. 

 Nostril strongly oblique, its inner corner nearer to mouth than to tip of snout by a dis- 

 tance about V2 as great as that between them, the anterior margin with a pronounced narrow 

 triangular lobe near the inner end; the distance between nostrils a little greater than % 

 breadth of mouth and about ^^ length of snout. Mouth broadly ovate, about i Vs times as 

 broad as high. Upper labial fold about % as long as nostril. 



Teeth '^~^°''_^'^ ; those at symphysis small, triangular, the base with or without 

 a blunt denticle on each side; uppers otherwise acute-triangular, increasingly oblique 

 toward corners of mouth, the inner margins nearly straight and smooth-edged on 

 cusps but more or less wavy or irregularly serrate basally, the outer margins strongly 

 notched, smooth toward tips, but with 2 to 4 very prominent serrations or low denticles on 

 basal sector, the distal serration considerably the largest; lowers symmetrical, more slender 

 than uppers, nearly erect, bases as well as cusps with smooth edges. 



First dorsal comparatively small, its anterior margin only about as long as snout in 

 front of mouth, and about % as long as pectoral, its origin about over inner corner of pec- 

 toral,* its anterior margin weakly convex, its posterior margin strongly concave basally, its 

 apex rounded, its free corner a little less than Yo as long as its base. Second dorsal a little 

 less than V2 as long as ist dorsal at base, relatively much lower, and only about V5 to % 

 as great in area, its apex broadly rounded, posterior margin only very weakly concave, its 

 free rear tip very slender and nearly as long as its base, its origin very little posterior to 

 origin of anal. Caudal about V4 of total length, with bluntly rounded tip, its terminal 

 sector about V4 the length of fin, the lower anterior lobe about 40% as long as upper mar- 

 gin, with rather broadly rounded tip. Interspace between caudal and anal about i V2 times 

 as long as base of anal. Anal about as high and long as 2nd dorsal and with similarly slender 



7. In the preserved state this ridge lies at the bottom of a groove of muscular contraction. 

 S. Its precise point of origin is difficult to determine in the preserved specimen. 



