256 THE PLAGIOSTOMIA. 



convex, outer border nearly straight. Dorsals about equal, rounded. A blunt 

 keel at each side of the tail in front of the caudal. Caudal as broad as long; 

 supracaudal rather broad, rounded; subcaudal vertically subtruncate, convex. 

 Scales with slender hooked cusps and broad bases. The cusp is subcorneal at 

 the apex and there are two keels in front of its basal portion and others at each 

 side. The modifications are those common to species of the genus. A specimen 

 of nine inches in length at the time of the loss of the yolk sac is naked; one of 

 twelve inches has the back and the outer parts of the lower surface covered with 

 scales and has a vertebral series of larger ones, besides a few others in groups at 

 the eyes and spiracles. At seventeen inches the scales of the middle of the back 

 are more placoid and larger and on the lower surfaces of the paired fins and the 

 tail the smooth flat-crowned imbricate scales have spread toward the middle, 

 which on still larger individuals is entirely covered with the exception of a 

 space below the throat and gills. 



Rusty to plumbeous brown thickly freckled with small spots to dots of darker. 

 Belly white, borders of lower surface with leaden brown which spreads toward 

 the middle. One example at hand has faint transverse bands of darker as wide 

 as the dorsal on the back: one across the nape, two between the bases of the 

 pectorals, three others between the ventrals and one in front of the first dorsal. 



Japan. 



Rhina nebulosa. 



Squalina nebulosa Regan, 1906, Ann. mag. nat. hist., ser. 7, 18, p. 439. 



"Outer nasal flap with entire edges; inner flap with two nearly simple pro- 

 longations, the outer of which has a fringed lobe at its base." Folds at the side 

 of the head forming two lobes with convex edges at each side, the second the 

 larger opposite the angle of the mouth. Spiracles not quite so far apart as the 

 eyes. Outer angle of the pectoral much more than a right angle. Ventrals 

 extending beyond the origin of the first dorsal. Posterior edge of the supracaudal 

 slightly emarginate; subcaudal nearly vertically truncate. "Upper surface 

 with small pointed denticles, each with three keels; no median series of enlarged 

 denticles; small imbricated denticles at outer edges of paired fins, extending on 

 to their lower surface and on the pectorals forming a strip about equal in width 

 to the distance between eye and spiracle; denticles on lower surface of tail not 

 extending forward to its base; lower surface of head and abdomen naked. 

 Brownish, obscurely marbled with blackish, and with a few small round whitish 

 spots." 



