yo Memoir Sears Foundation for Marine Research 



GUI openings: lengths, ist 1.4, 1.4; 3rd 1.6, 1.5; 5th i.i, 1.2; distance between 



inner ends, ist 11.6, 12.3; 5th 7.7, 8.6. 

 First dorsal fin: vertical height 6.2, 6.8; length of base 4.7, 5.1. 

 Second dorsal fin: vertical height 6.5, 6.7; length of base 4.9, 5.1. 

 Caudal fin: upper anterior margin 15.1, 15.4. 

 Pelvics: origin to tip 15.1, 15.4. 

 Distance: from tip of snout to center of cloaca 41.8, 42.5; from center of cloaca 



to tip of tail 58.2, 57.5. 

 Interspace between: ist and 2nd dorsals 11.3, 11.3; 2nd dorsal and caudal 



6.1, 5.8. 



R.percellens resembles R. lentiginosus so closely in appearance, in proportional 

 dimensions generally, in shapes and locations of fins, and in the shapes of the dermal 

 denticles on different parts of the body, that the points of difference alone need be 

 noted. These are: Rostral cartilage narrower, less spatulate in form, its maximum breadth 

 near tip of snout only about as great as distance between inner ends of nostrils, the two 

 ridges close together and parallel for a little more than half their length but diverging 

 a little rearward. Upper tip of snout without enlarged tubercles (but see p. 68). The 

 outer of the two folds on the posterior margin of spiracle averaging a little longer re- 

 latively. Nostril I— 1.2 times as long as distance between nostrils; the inward extension 

 of anterior nasal flap ending more abruptly, perhaps averaging a little shorter relatively 

 (Fig. 12). White dots on upper surface much less numerous (when present) than on 

 spotted specimens of lentiginosus and arranged in symmetrical pattern on both sides of 

 midline; also, the majority of specimens more or less definitely marked with dark 

 blotches or incomplete crossbars. 



The enlarged tubercles low, either rounded transversely or with median ridge 

 sloping forward; about 36-46 in midline of back from nuchal region to first dorsal 

 in adults, the smaller ones irregularly interspersed with larger ones; about 3—7 in inter- 

 space between first and second dorsal fins; 1-3 on each shoulder; -^-d close in front 

 of orbit, with 2—7 of various sizes around inner margin of orbit to inner end of spiracle; 

 none over outer end of pectoral girdle. 



Color. Olive gray, reddish brown, or chocolate brown above; an extensive pale 

 translucent area on either side of rostral ridges; sides usually with darker brown spots 

 or blotches, vaguely outlined and varying in number, often forming indistinct cross- 

 bars on tail ; dorsals and caudal partly dusky, but outer margins of pectorals paler than 

 general ground tone; most specimens with up to about 40—45 indistinct whitish spots 

 on either side of midline, about as large as pupil, irregularly distributed, but arranged 

 symmetrically on the two sides of trunk. Lower surface pale yellowish, greyish or dusky 

 white, the tip of the snout with a more or less conspicuous sooty blotch, either solid 

 or more or less interrupted; diamond-shaped in young specimens but usually spreading 

 rearward with growth along margins of head as illustrated in Fig. 16B. 



Relation to Extralimital Species. Among eastern Atlantic species, R.percellens 



