21. TRYGONID^ DASYATIS. 
47 
with half spots of paler. Tail with four dark blotches above, forming 
half rings. (Caudal spine wanting in all the specimens examined.) Vir- 
ginia to Brazil ; not uncommon. 
(liaia maclura Le Sueur, Jouru. Ac. Nat. Sci. Pliila. 1817, 41 ; Duiu6ril, Hist. Nat. 
Poiss. i, G14 ; Gunther, viii, 487.) 
60. P. marmorata Cooper. 
Disk about twice as broad as long, covered with perfectly smooth skin. 
Tail ill length of disk, with a rather small cutaneous fold above and 
below, the lower fold the longer, the upper about as deep. Interor- 
bital space a little shorter than the snout. Snout slightly lirominent, 
but forming a very obtuse angle. Olive-brown, finely mottled every- 
where with darker, the dark forming reticulations around pale roundish 
spots. Tail without dark rings. Caudal spine much smaller than in 
other sting rays ; present in all specimens examined. Coast of Califor- 
nia from Point Concepcion southward ; common. 
(Cooper, Proc. Cal. Ac. Nat. Sci. iii, 112.) 
40.— DASYATIS Rafiuesque. 
Sting Bays. 
{Trygon Adanson.) 
(Rafiuesque, Caratteri cli Alcuui Nuovi Gen. 1810, 16: type Dasyatis ujus Rafiuesque = 
Baia jiastinaca Liuuaeus.) 
Disk oval, flat, with rounded angles. Tail very long and slender, 
whip-like, without fin, but often with one or two vertical membranace- 
ous folds. A strong serrated spine toward the base of the tail. Skin 
more or less spinous or pricklj', rarely smooth. Teeth small, paved. 
A few iiapillm usually present in the mouth behind the lower jaw. 
Sting rays of large size, abundant iu warm seas. Many of the spinous 
species are nearly or (piite smooth when young, {datru-, shaggy or 
rough; a skate; hence properly Dosy/wtis.) 
* Ul)pcr caudiil fold obsolete; lower well developed. (Ilcmitrygon Muller tfc lleule.) 
61. D. cciitriiriis (Mitclull) Jordan & Gilbert . — Common Sting Bay ; Clam Cracker; 
Stingarce. 
Disk a little broader than long, its anterior angle obtuse. Tail rel- 
atively stout, about one-third longer than the disk. xY well-developed 
fold below, but the ujtper fold reduced to a mere trace. Disk perfectly 
smooth in the young, with more or less of tubercles along the median 
line of the back and the scapular region in the adult. Buccal papilloB 
3. Width of mouth about half its distance from the tip of the snout. 
