The True Sharks 213 
rounded disk, and a stout, short tail with a caudal fin. It has a 
strong spine, and for its size is the most dangerous of the sting- 
rays. Urolophus halleri, the California species, was named for a 
young man who was stung by the species at the time of its first 
discovery at San Diego in 1863. Uvrolophus jamaicensis abounds 
in the West Indies, Urolophus mundus at Panama, and Urolo- 
phus fuscus in Japan. None of the species reach Europe. The 
true sting-ray (stingaree, or clam-cracker), Dasyatis, is more 
widely diffused and the species are very closely related. In 
these species the body is angular and the tail whip-like. Some 
Fie. 154 —Sting-ray, Dasyatis sabina Le Sueur. Galveston. 
of the species reach a length of ten or twelve feet. None have 
any economic value, and all are disliked by fishermen. Dasyatis 
pastinaca is common in Europe, Dasyatis centrura along our 
Atlantic coast, Dasyatis sabina ascends the rivers of Florida, 
and Dasyatis dipterura abounds in the bay of San Diego. Other 
species are found in tropical America, while still others (Dasyatis 
akajet, kuhlii, zugei, etc.) swarm in Japan and across India to 
Zanzibar. 
Pteroplatea, the butterfly-ray, has the disk very much broader 
than long, and the trivial tail is very short, its little spine more 
often lost than present. Different species of this genus circle 
the globe: Pteroplatea maclura, on our Atlantic coast; Ptero- 
platea marmorata, in California; Pteroplatea japonica, in Japan; 
