80 Bulletin 47, United States National Museum. 



Urolophus, MULLEB & HENLE, Plagiostomen, 1838, 173, (aurantiacus = cruciatus). 

 Urotrygon, GILL, Proc. Ac. Nat. Sci. Phila., 1863, 173, (mundm). 



Disk oval or rhombic, the length and breadth not very unequal ; snout 

 rounded or the tip exserted ; skin smooth or more or less prickly. Tail 

 rather short, little if any longer than the disk, muscular, provided with 

 a distinct rayed caudal fin j no dorsal fin. Upper part of the tail with a 

 strong serrated spine. Warm seas. Sting rays of small size, the most 

 vigorous and most dangerous of the group, mostly confined to tropical 

 America, (ovpu, tail ; A6$of, crest.) 



a. Middle line of back or tail with no enlarged shields, spines or prickles, the skin smooth or 



with prickles similar to those found elsewhere; disk roundish, the snout not prominent. 



b. Skin everywhere perfectly smooth; snout little prominent; tail shorter than disk; 



body with yellow streaks and spots. HALLEBI, 114. 



bb. Skin more or less prickly above. 



c. Skin mostly smooth, some weak prickles present on middle of back. 



NEBULOSUS, 115. 

 cc. Skin above everywhere beset with small prickles. 



d. Tail rather shorter than disk, which is longer than broad. Color brown, 



everywhere sprinkled with yellow dots. JAMAICENSIS, 116. 



dd. Tail rather longer than disk, the caudal spine inserted behind its middle; disk 



as broad as long; prickles stellate. Color plain brownish. MUNDUS, 117. 



oa. Middle line of back or tail with 1 or more enlarged spines or prickles; tip of snout more or 



less prominent. Color nearly plain. 



e. Middle of back with 1 or 2 stout spines; no spines on tail; rest of disk smooth or 

 slightly prickly; disk broader than long, shorter than tail. GOODEI, 118. 



ee. Middle of back without differentiated spines; median line of tail with spines. 



/. Median line of tail with 2 to 8 strong, broad rooted spines; rest of body entirely 

 smooth; tail longer than disk which is slightly longer than broad; the snout 

 strongly projecting. ASPIDUBUS, 119. 



ff. Median line of back and tail with 18 to 22 recurved spinules; these largest on tail; 

 disk above mostly covered with small stellate prickles; snout slightly pro- 

 jecting; tail as long as disk, which is slightly broader than long. 



ASTERIAS, 120. 

 114. UROLOPHUS HALLERI, Cooper. 



Disk nearly round, a little broader than long, with the anterior margins 

 straightish, meeting in a slight angle. Snout (from the eyes) longer than 

 the width of the iuterorbital space ; less than i disk. Tail somewhat 

 shorter than the disk. Teeth obtuse in both sexes. Skin perfectly smooth, 

 without spines or prickles. Color light brownish, with marblings and 

 wavy lines of yellowish and dusky, sometimes with yellowish spots, occa- 

 sionally with wide, obscure dusky streaks, which are crossed by similar 

 transverse streaks ; belly yellowish tinged. Coast of California from 

 Point Concepcion southward to northen Mexico ; exceedingly abundant in 

 sheltered bays. L. 12 inches. The smallest of our sting rays. Closely 

 related to the Australian U. cruciatus. (Named for Mr. Haller, of Port 

 Townsend, Washington, who, as a boy, was stung by this species at San 

 Diego in 1862.) 



Urolophus halleri, COOPER, Proc. Cal. Ac. Sci., 1863, in, 95, San Diego ; JORDAN & GILBERT, 

 Synopsis, 46, 1883. 



115. UROLOPHUS NEBULOSUS, Garman. 



Disk nearly round, formed much as in U. halleri. Skin not quite 

 smooth, some asperities present about the middle of the back; no median 



