ADDENDA TO MARSIPOBRANCIIIJ, ELASMOBRANCIIII, ETC. 71 



termination. Mouth with five papillae, outer small. Teeth small, blunt. 

 Upper jaw indented in the middle; lower with a prominence in front, 

 Disk naked in the young* Adult specimens have three rows of tubercles 

 on the middle of the back disposed as are those of D. kastata. A large 

 specimen from Payta has three large, erect, broad-based tubercles in 

 front of the caudal spine, and the tail rough with smaller ones. The 

 short rows on the shoulders contain from three to four, and probably 

 increase in number with age, as is the case with the closely allied Atlan- 

 tic coast species. Color light grayish or olivaceous brown, reddish near 

 the edges, white below, with round spots of brownish under the base of 

 the tail. Compared with D. liastata this species differs in the shorter 

 tail, rounder extremities of the disk, and the shape and size of the tu- 

 bercles and membraneous fins. D. liastata has no expansion on the top 

 of the tail, and that on the lower side is very long, of moderate width, 

 and tapers gradually. Those of D. brevis are comparatively short and 

 broad ; they rise gradually and terminate abruptly. From D. sayi this 

 species is to be distinguished by the great development of the caudal 

 expansions, their shape and length, and by the tubercles on shoulders 

 and tail. A large female measures in length of body 17, tail 23, and 

 width of pectorals 18 inches. A young male in length of body 8.1, tail 

 12, and width of pectorals 9.2 inches. Peru. 



DASIBATIS DIPTERURA. 



(Jordan & Gilbert. 1880, Proc. U. S. Nat. Mus. 31.) 



Disk rhomboid, slightly broader than long : anterior margins nearly 

 straight forwards, meeting in a very obtuse angle; posterior margins 

 curved ; lateral angles rounded. Tail nearly half longer than disk, with 

 a conspicuous cutaneous fold below, and a smaller but evident one above. 

 Upper jaw considerably curved, with a slight convex protuberance in 

 front, which fits into a slight emargination in the lower jaw, which is 

 convex, its outlines corresponding to the curves of the upper jaw. 

 Bands of teeth wider in front than laterally. Inside of mouth, behind 

 the lower jaw, with three fleshy processes. Teeth about f; about 8 in 

 a cross-series in the upper jaw, and 10 in the lower. Color light brown, 

 somewhat marbled with darker, but without distinct spots ; tail black- 

 ish ; belly white. Skin everywhere perfectly smooth in the young ; adult 

 with small tubercles along the back. San Diego, Cal. 



Of the nine species enumerated above as belonging to American 



