546 Memoir Sears Foundation for Marine Research 



of body from snout to termination of caudal fin. Trunk strongly compressed laterally 

 posterior to head, increasingly so rearward, its thickness about ^/^ as great as its height 

 opposite bases of pelvic fins. 



Skin perfectly smooth on immature specimen, except closely pock-marked with 

 many depressions of different sizes on top and on upper sides of head abreast of mouth 

 and nostrils and toward tip of snout. 



Lateral mucous canal with a short and abrupt wave opposite the anterior part of 

 the first dorsal fin, after which there is a long low dip opposite the origin of the second 

 dorsal fin, thence continuing nearly straight along rear part of trunk, descending at 

 origin of caudal fin to follow out along lower edge of caudal axis; junction of cranial 

 canal with aural canal somewhat more acute than a right angle; anterior course of 

 cranial canal nearly straight, looping down in front of eye; jugular and oral canals 

 running downward from suborbital as a joint canal for a short distance before separating. 

 About 10-12 medium-size pores close in front of occipital canal; about 12 pores in 

 area bounded by suborbital and joint oral-jugular canals; about 10 large openings along 

 angular canal to front of snout; a single row of about 15 small pores descending parallel 

 with oral branch and continuing in front of it; about 8—9 large openings along anterior 

 part of suborbital canal from its descending wave to front of snout; jugular canal con- 

 tinued downward onto throat as a series of short slits. 



Head about 21 "/o of length of trunk to upper origin of caudal fin. Snout conical 

 with blunt tip. Eye oval, sloping a little rearward, its horizontal diameter about 1.3 

 times its vertical diameter; distance from tip of snout to front of eye about Vs of length 

 of head to origin of pectorals; pupil half of vertical diameter of eye; height of eye about 

 ^/s of height of head, its length about Vs of length of head to origin of pectorals. Gill 

 openings nearly half as long as distance from tip of snout to front of eye; distance across 

 throat between lower ends of gill openings about half as long as eye; fold across throat 

 strongly marked. Exposed subdivision of nostrils crescentic on inner edge, about 1.5 

 times as long as broad, its length about 15 «/o as great as length of eye; distance from 

 its own rear edge to free edge of upper lip about as long as its own length. Width of 

 mouth, when closed, a little less than length of eye. 



Anterior upper (vomerine) dental plates quadrate, their outer anterior outlines 

 convex, with six radial ridges. Posterior upper (palatine) plates about 2.75 times as 

 long as anterior plates, triangular, the posterior margin about -/s as long as outer margin, 

 surface lumpy, with four prominent ridges running longitudinally. Lower (mandibular) 

 plates nearly as long as posterior upper plates, each plate with a double concavity and 

 central ridge on inner surface, the cutting edge uneven, highest at center of mouth. 



Dorsal spine about as long as distance from tip of snout to rear edge of pupil, 

 reaching slightly beyond apex of first dorsal fin; outer part free from first dorsal fin, 

 the rear face with two rows of low sharp thorns pointing toward base. First dorsal fin 

 with sharp angle at apex and straight posterior margin; its base from origin of spine to 

 bottom of interdorsal notch nearly as long as height along anterior margin of fin. 

 Distance between first dorsal (when slightly depressed) and the first noticeable elevation 



