Jordan and Everman-n. Fishes of North America. 79 



than first; ventrals large, adnate behind. Color brown, mottled and 

 spotted above with lighter and darker; center of disk with a large, 

 blackish, ocellated spot, the darker center surrounded by a pale ring, a 

 pale spot at center; ocellus as long as snout, Panama, rare. (6//^r6f, 

 cvcd, from the color markings.) 



Discopyyeommata, JORDAN & GILBERT, Proc. U. S. Nat. Mus., 1889, 151, Panama. (Type, No. 41133.) 



Suborder MASTICURA. 



(THE WHIP-TAILED RAYS.) 



Family XXVI. DASYATID^. 



(THE STING RAYS.) 



Disk usually more or less broad than long; the pectoral fins uninter- 

 ruptedly confluent in front, forming the tip of the snout ; tail variously 

 formed, usually whip-like, sometimes short and stout, sometimes bearing 

 a single dorsal or caudal fin, but never with 2 dorsals; usually 1 or 

 more vertical folds of skin on the tail, rarely a lateral fold. Tail gener- 

 ally armed with a large, sharp, retrorsely serrate spine on its upper sur- 

 face toward the base ; 2 or 3 spines occasionally present. Ventral fins 

 not emarginate. Skin smooth or variously prickly or spinous, rough- 

 est in the adult ; no differentiated spines on the pectorals in the males, 

 the sexes being similar. Mouth rather small ; teeth small, paved, 

 usually more or less pointed or tubercular. Nostrils close together ; nasal 

 valves forming a rectangular flap, which is joined to the upper jaw by a 

 narrow frenum. Spiracles large, placed close behind the eyes. Skull not 

 elevated, the eyes and spiracles superior. Ovoviviparous. Genera about 

 10 ; species 50. Found in most warm seas, some of them in the fresh 

 waters of the northern parts of South America. The large, jagged spine 

 on the muscular tail is capable of inflicting a severe and even dangerous 

 wound. (TRYGONID^E, Giinther, Cat., vin, 471-488.) 



UBOLOPHINA: : 



a. Tail stout, provided with a rayed caudal fin; no dorsal fin; disk roundish ; caudal spine 

 strong. UROLOPHUS, 52. 



DASYATIN.E : 



aa. Tail slender, without caudal fin; pelvis without sword-shaped* process. (Marine species). 

 b. Tail whip-like, longer than the disk which is rhomboid or roundish; caudal spine strong. 



DASYATIS, 53. 



bb. Tail very short, shorter than the very broad, transversely rhombic disk; caudal spine 

 weak, often wanting. No trace of dorsal fin. PTEROPLATEA, 54. 



52. UROLOPHUS, Miiller & Henle. 

 (ROUND STING RAYS.) 



Leiobatm, f BLAINVILLE, Jour. Phys., LXXXIII, 1816, 262, (cruciatus; not Leiobatw, Rafinesque, 

 1810). 



* In the fresh water genera Ellipesurus and Paratrygon, species of which are found in the waters 

 of Colombia, Venezuela, and Guiana, the pelvis has a sword-shaped continuation or process. 

 See Garman, Proc. Bost. Soc. Nat. Hist., 1877, 210, and Steindachner, Fische des Magdalenen- 

 stromes, 1878,58. 



tin the Faune Francaise, 1828, Blaineville changes "bates" in this and all similar names to 

 "bate," thus Leiobatis, Aetobaiis, 



