388 CALIFORNIA ACADEMY OF SCIENCES. 16 
a third procured by Mr. James A. Richardson in the 
harbor of La Paz. Specimens had also been obtained by 
Dr. Gilbert, at Panama, in 1883, but having been de- 
stroyed by fire, the species has remained undescribed 
until the present time. 
Snout 334 in length of disk; preocular part of snout 
equals preoral; interocular space in snout, 1%; width of 
mouth, 2%. Eye much smaller than spiracle; spiracles 
edged with small tubercles. Length of disk equal to its 
width; disk equal to length of tail, without caudal fin; 
tail with a loose told of skin on each side. First and 
second dorsals equal, rounded behind; ventrals large, 
ending midway between posterior edge of disk and caudal 
fin. Color: Pale olive brown, a little clouded with 
darker; second dorsal edged with pale; dots on head 
dusky. , 
Length of largest: specimen,’ 20 inches: “ype. Ne: 
1699, "5: Jr Univ. Mus. 
The Spanish name Axtemedor seems to be equivalent 
to /ntimidator. 
Family DASYATIDA. 
14. Urolophus asterias Jordan & Gilbert. Rata. 
Very common in the surf and-on the sandy beaches 
about Mazatlan. Spinules on back and tail 18 to 32 in 
number. The upper side of the disk is marked with 
round dusky spots, faint, as if washed or faded out. 
15. Urolophus rogersi Jordan & Starks, n. sp. 
Disk broader than long by a distance 2% times the 
interorbital width; anterior margins of disk nearly straight, 
the tip of snout projecting; snout from eye, 334 in length 
of disk; eyes little smaller than spiracles; width of mouth, 
2% times in preoral part of snout; caudal spine inserted 
in front of middle of tail. Skin with minute prickles on 
