22 SELACHII: RALE. — V. 
21. TORPEDO Duméril. 
30. T. occidentalis Storer. Torrepo. Cramp-riss. NumB- 
FisH. Black, with obscure darker blotches; spiracles with entire 
edges. L. 3 to 5 feet. Cape Cod S.; not common. 
Famiry XVI. DASYATIDAS. (Tue Stixc-Rays.) 
Disk broad, the pectorals confluent anteriorly, forming tip of 
snout; tail, usually whip-like, sometimes short and stout, with or 
without fins, but never with two dorsals. ‘Tail usually armed with 
a sharp, retrorsely serrate spine above, near the base (this often 
duplicated and sometimes wanting): ventral fins entire. Skin 
smooth or variously rough, the adult roughest. Mouth small, with 
small teeth. Sexes similar. Genera 10, species 50, in most 
warm seas. -The large spine or “sting ” on the tail in most species 
may inflict a dangerous wound. 
a. Tail slender, whip-like, without caudal fin, ig than the disk; ‘‘sting’’ 
on tail strong. . - i teh “is DasyAtis, 22. 
aa. Tail very slender and slit, décter ts the very broad disk: sting 
minute or wanting... . . . . + + + + + + PTEROPLATEA, 23. 
22. DASYATIS Rafinesque. (Trygon Adanson.) 
(Sacvs, shaggy or rough; Baris, skate.) 
w., Tail with a fold on its lower margin only, the upper edge rounded. 
31. D. centrurus (Mitchill). Common Stinc-Ray. Cram- 
Cracker. StTincaREE. Snout not prominent; disk a little wider 
than long; tail usually not quite twice length of disk. Adult 
with some stellate tubercles on back and tail. Color olive-brown. 
L. 12 feet. Cape Cod S., common. (kévrpov, spine; ovpd, tail.) 
aa. Tail with a fold of skin on its upper as well as lower margin. 
32. D. say (Le Sueur). Souruern Stinc-Ray. WHIp- 
PAREE. Snout not prominent; disk a little wider than long; tail 
nearly twice length of disk. Body and tail without large spines. 
N. Y.,S. (To Thomas Say, a distinguished zodlogist.) 
23. PTBROPLATEA, Miller & Henle. 
33. P. maclura (Le Sueur). Butrerrity Ray. Disk nearly 
twice as broad as long, three times as long as tail; sting on tail 
usually obsolete. Olive-brown, finely marbled and speckled ; tail 
with four dark blotches: front edge of disk with pale half-circular 
spots. Va.S. (To William Maclure.) 
Famiry XVIL AETOBATIDA. (Tue Eacuz Rays.) 
Pectoral fins interrupted, reappearing on tip of snout as one or 
two detached appendages or cephalic fins; skull somewhat elevated, 
so that eyes and spiracles are lateral; teeth large, flat, hexangular, 
