350 THE PLAGIOSTOMIA. 



Raia mammillidens. 



Raia mammillidens Alcock, 1889, Ann. mag. nat. hist., ser. 6, 4, p. 380; 1892, III. zool. Investigator, 

 pi. 8, f. 1; 1899, Cat. deep-sea fishes Indian mus., p. 19. 



Disk rhomboid, width or length, including the ventrals, about half of the 

 total length; angles rounded, anterior and outer greater and hinder less than 

 90°; anterior margins slightly waved and but little convex; angle at the snout 

 nearly 90°, blunted. Snout short, length less than one fourth of the width of 

 the disk, little more than the distance between the outer margins of the nostrils. 

 Length of orbit equal width of interorbital space. Mouth arched, crescentic; 

 teeth of a female with a globular base and a mammillary point, in about 24 rows. 

 Entire upper surface covered by small sharp close-set spines; lower surfaces 

 smooth. A large spine in front of and another behind each eye, one above 

 each spiracle, two or three above each shoulder, and a median vertebral series 

 on back and tail. Dorsal fins slightly separated, tail little produced behind the 

 second. 



Uniform jet black, in spirits dark chocolate. 



Type a female of 1 15 inches, from the Gulf of Menar, at a depth of 597 

 fathoms. 



Raia porosa. 



Raia porosa Gunther, 1S74, Ann. mag. nat. hist., ser. 4, 13, p. 154. 



Allied to Raia marginata. Width of disk much more than its length, 

 including the ventrals; anterior margins undulated; front part of snout ab- 

 ruptly contracted into a narrow thin appendage. Teeth in 54 or 56 rows, 

 pointed in male, flat in the female. A series of spines on each orbital ridge; 

 rostral process with small stellate spines; a series of three or four spines on the 

 median line of the back behind the head. Tail with three series of spines on 

 the male and five on the female. Male with tenacula near the outer angles of the 

 disk, with large spines on each side of the head, and with the anterior margins 

 of the disk covered with small spines on its upper side in its whole length ; female 

 smooth in the parts just mentioned, with a broad band of small hooks along the 

 upper side of the hinder margins. 



Skin of lower part of snout and of throat with many large pores white in 

 the centre and edged with black. Upper parts brown, snout white; lower 

 parts whitish, tinged with brown. 



Two specimens, male and female, adults, 11 inches in length, from China. 



