ADDENDA TO MARSIPOBRANCniI, ELASMOBRANCIIII, ETC. 71 
termmation. Moutli with five papillae, outer small. Teeth small, blunt. 
Upper jaw iudeuted ill the middle; lower with a promiueuce in front, 
Disk naked in the young. Adult specimens have three rows of tubercles 
ou the middle of the back disposed as are those of D. Mstata. 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 ou the shoulders contain from three to four, and jirobably 
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. hastata this species differs in the shorter 
tail, rounder extremities of the disk, and the shape and size of the tu- 
bercles and membraneous tins. D. hastata 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 distinguislied 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 
12j and width of pectorals 9.2 inches. Peru. 
Dasibatis dipterura. 
(Jordan &, Gilbert, 1S80, Proc. U. S. Nat. Miis. 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 smallerbut evident one above. 
Upper jaw considerably curved, with a slight convex iirotuberance 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. 
Bauds of teeth wider in front than laterally. Inside of mouth, behind 
the lower jaw, with three fleshy processes. Teeth about f j; about 8 in 
a cross-series in the u])per jaw, and 10 in the lower. Color light brown, 
sxnnewhat 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 
