PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 521 



moderate, rather larger than the spiracle. Spiracle with one tubercle 

 on the hinder margin. Anterior nasal valves dilated, extending across 

 about one-third of the space between the nostrils. Mouth arching 

 forward slightly. Body rough with shagreen above and below. Small 

 hooked spines scattered over back and tail. A row of tubercular spines 

 along the vertebrae to the second dorsal. Two or three similar tuber- 

 cles over each extremity of the shoulder-girdle and a pair a short dis- 

 tance from these toward the vertebral row. A couple of spines above 

 each spiracle and one or two in front of each eye. Tail depressed, with a 

 fold on each side. Dorsals equal, second distant from the caudal the 

 length of its base and from the first the length of its anterior border. 



Light grayish or olivaceous brown 5 margins lighter ; whitish below. 

 Sometimes clouded with brown. 



The claspers, as far as may be judged from young specimens, are 

 similar to those of R. nndulatus. 



Total length 18J, length of disk, including ventrals, 10, and width of 

 disk 8| inches. 



Eio Janeiro. 



Syrrhina exasperata. 



Jord. & Gilb. 1880, Proc. U. S. Nat. Mns. 32. 

 Disk, including the ventrals, rhombic, longer than wide. Anterior 

 borders of pectorals nearly straight ; posterior convex. Snout truncated, 

 as wide on the end as the space between the eyes. Rostral cartilage 

 wide and strong, deeply grooved on its upper surface. Ilostral ridges 

 prominent, widely separated, nearly or quite parallel from base to ex- 

 tremity. Spiracles large, equal in diameter to the orbit, without a fold 

 on the side. Fin-angles rounded, except the obtuse posterior angles of 

 the dorsals. Dorsals elevated, behind the ventrals, the length of the 

 base of tlie first less than the length of its posterior border, base of the 

 second equal to its posterior margin. The base of the first is equal to 

 its distance from ventral or from second dursal. Anterior nasal valves 

 dilated, continued a little beyond the inner angles of the nostrils ; pos- 

 terior two-lobed. Anterior extremities of the pectorals widely separated 

 from the rostral cartilage, extending very little in advance of the eyes. 

 Mouth wide, forming a low arch, regularly curved from the corners. 

 Labial fold distinct for a short distance at the symphysis. Teeth small, 

 blunt, in a hundred and ten series in the ni)per jaw. Claspers long, 

 slender, knobbed at the ends. Tail with a thick fold on each side; 

 caudal tin rounded, without indentation. Back thicklj^ covered with 

 small scales, among which are scattered larger ones. A median row 

 of large, blunt tubercles on the back and tail, and two short rows 

 parallel to this on each shoulder. The bases of the tubercles are so 

 covered by the skin and small scales that they appear as rounded i)rom- 

 inences with a small spine on the summit. 



Color grayish brown. Near the ends of the rostral ridges there is a 



