362 THE PLAGIOSTOMIA. 



hind margins little convex; hind angles rounded. Orbit more than one half of 

 the interorbital width, or nearly one fifth of the preorbital length. Mouth wide, 

 width about three fifths of the preoral length, somewhat curved forward in the 

 middle. Outer lobes of palatal velum hardly developed, median notch deep. 

 Teeth small, crown flattened, hind edge sharp, more often angled toward the 

 throat, in ff rows. Top of disk and lower surface of snout rough with small 

 spines, rather loosely placed, larger on the head and along the middle of the back 

 and tail; a row of still larger ones, or small tubercles on each orbital ridge; 

 a row of eighteen compressed backward-directed tubercles on the median line of 

 the tail from the body to the second dorsal, three of them in the interdorsal space. 

 This median row no doubt extends forward on the body on large individuals. 

 Tail from the pores half of the total length, shorter than the pectorals; lateral 

 folds prominent. Dorsals rather large, on the hindmost third of the length of 

 the tail, separated from one another by little more than the base of the first. 

 Base of second dorsal equal two thirds of its distance from the end of the tail. 



Total length of specimen here described 22 inches, snout to abdominal pores 

 11, and greatest width 15 inches. 



Rusty brown, sprinkled on head and disk with small rounded spots of black; 

 lower surfaces lighter; openings of pores black, above and beneath. 



A large species, said by Ribeiro to measure more than a metre in length of 

 disk when fully grown. 



Rio Janeiro. 



Raia cyclophora. 



Rata cyclophora Regan, 1903, Proc. Zool. soc. London, 2, p. 60; Ribeiro, 1907, Arch. Mus. nac, 14, p. 

 178, pi. 16. 



Snout with an obtuse triangular projection of moderate length. Anterior 

 borders of pectorals emarginate. Eye-diameter two sevenths to one fourth of 

 the distance from the end of the snout; equal to interorbital width. Mouth 

 strongly curved; teeth in 36-38 rows. Body smooth, excepting a series of ten 

 to eleven spines on the dorsal surface of the tail, and, on males, a double series 

 of curved tenacula on each pectoral. Claspers of the male extending to below 

 the first dorsal. 



Brownish, with a conspicuous black circle on each pectoral near the middle 

 of its base. 



Types two specimens from Rio Janeiro; a female 480 mm. in total length, 

 and a male of 410 mm. 



