5 8 Memoir Sears Foundation for Marine Research 



Dermal denticles minute, close-set, mostly spear-shaped and rounded anteriorly 

 over upper surface in general from nuchal region rearward, but some more ovate with 

 skin more or less exposed between them; those on crown narrower, fluted anteriorly; 

 those on snout flat, roundish to ovate; those on lower surface rounded to tetragonal 

 with blunted corners, varying in size, so close-spaced that the skin is nearly or wholly 

 concealed. Midline of back rearward from nuchal region with a more or less regular 

 row of tubercles, each with sloping median ridge, more prominent than those oi R. lenti- 

 ginosus and of R. percellens but irregularly interspersed with smaller; up to about 70 

 tubercles to first dorsal fin, about 8 to 12 between dorsals, and a few smaller ones close 

 beyond rear end of second dorsal; each shoulder with 2—4 somewhat lower tubercles, 

 with one over each outer end of pectoral girdle*^ on small as well as on large specimens; 

 4—7 larger and smaller and more conical ones close in front of orbit; 2-6 along inner 

 margin of orbit, with one or two close to inner end of spiracle; tip of snout with 2—4 

 small rounded tubercles on small and on some medium-sized specimens but without 

 tubercles on large ones. 



Snout in front of orbits about 3.7 times as long as distance between orbits in 

 young, about 4.0 times as long in large specimens of both sexes; its length in front of 

 mouth about 3.0 times as great as width of mouth in young and about 3.3 times as 

 great in larger specimens. Horizontal diameter of eye about half as long as distance 

 between spiracles. Length of orbit plus spiracle about "Is—^U as great as distance between 

 spiracles. Spiracles about V4 as long as orbit, nearly transverse, posterior margin with 

 two well marked folds or ridges, the outer the longer. First to fourth gill openings of 

 about equal lengths, about half as long as nostril, the fifth a little shorter; distance 

 between inner ends of fifth gill openings about 1.6 times as great as breadth of mouth. 

 Nostrils moderately oblique, their length about 1.5 times as great as distance between 

 them and about ^/^ (63—66 "/o) as great as width of mouth; anterior margin expanded 

 near the middle as a narrow lobe with rounded tip, curving outwardly and across nasal 

 aperture and extending inward a short distance as a narrow fold that ends abruptly 

 without encroaching on the internarial space; posterior (outer) margin of nostril ex- 

 panded as three confluent flaps, two of them shorter and directed rearward, the third 

 longer, digitate, originating about opposite anterior nasal flap and extending along 

 nasal aperture about 40 '/o of the distance from its own origin toward inner corner of 

 nostril. 



Teeth l^^l in specimens 515—790 mm long, those of immature specimens close- 

 set in quincunx; low, oval, the longer axis transverse, with indistinct transverse cutting 

 edge; the base extending a little rearward much as in R. Ientigiyiosus\ those of mature 

 males not seen. 



First and second dorsals about equal in size, triangular, with abruptly rounded 

 corners, their anterior margins straight or slightly convex, the posterior margins straight 

 or slightly concave and approximately vertical, the free rear corner about V2— ^/s ^s long 



43. The type specimen had no tubercles over the outer ends of the pectoral girdle (Miiller and Henle, Plagiost., 1841 : 

 122), but they are present on all that we have seen. 



