PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 52? 
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 vertebr 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; 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. undulatus. 
Total length 183, length of disk, including ventrals, 10, and width of 
disk 5? inches. 
Rio Janeiro. 
Syrrhina exasperata. 
Jord. & Gilb. 1880, Proc. U. S. Nat. Mus. 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. Itostral cartilage 
wide and strong, deeply grooved on its upper surface. Tostral 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 the 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 dorsal. 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 distinet for a short distance at the symphysis. Teeth small, 
blunt, in a hundred and ten series in the upper jaw. Claspers long, 
slender, knobbed at the ends. Tail with a thick fold on each side; 
caudal fin rounded, without indentation. Back thickly 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 prom- 
inences with a small spine on the summit. 
Color grayish brown. Near the ends of the rostral ridges there is a 
