Fishes of the Western North Atlantic 433 



Range. So far known only from a single specimen, collected by the USS Niagara 

 in the Gulf of Venezuela at Point Macolla, April 19, 1925. 



Reference : 



Urotrygon venezuelae Schultz, Proc. U.S. nat. Mus., 99, 1949: 24 (descr., meas., ill., Gulf of Venezuela). 



Family MTLIOBATIDJE 

 Eagle Rays 



Characters. Myliobatoidea with pectorals either narrow opposite eyes or entirely 

 interrupted there, the head thus being conspicuously marked off from the body. Ante- 

 rior subdivisions of pectorals united across front of head below tip of snout, forming 

 a single subrostral lobe. Anterior contour of cranium nearly straight centrally, rounded 

 at outer corners. Crown conspicuously elevated. Tail much longer than disc, slender, 

 armed with a serrate spine (or spines) in some species but not in others. A small dorsal 

 fin on anterior part of tail, but no caudal fin. Eyes and spiracles on sides of head.i 

 Nasal curtain with fringed margin, roofing over all but outermost ends of nasal ap- 

 ertures. Mouth on ventral surface; transverse curtain on roof of mouth coarsely fringed; 

 fold overlapping youngest rows of teeth with or without transverse rows of papillae, its 

 free anterior margin thick and fleshy, either nearly smooth or bordered with low blunt 

 knobs. Floor of mouth posterior to dental plate with several papillae. Gill openings little 

 if any longer than eye. Teeth in i —7 series only, flat and pavement-like, the median 

 series much the largest if there be more than one series; several rows in function 

 simultaneously. Skin naked except for tail spine (or spines), or with tubercles around 

 orbits and along midline of back on males. Pelvis more or less strongly arched, with 

 shorter or longer median process, directed forward, but without lateral processes. ^ 

 Anterior and posterior surfaces of gill arches, inward from gill filaments, each with a 

 series of fleshy knobs or papillae widely spaced. No electric organs. Characters otherwise 

 as in the Dasyatidae (p. 2)'iS)- 



Remarks. The tail spines of such myliobatids as possess them are venomous, to 

 judge from the clinical effects of wounds by the Spotted Eagle Rays {Aetobatus), the 

 only genus for which information is at hand (p. 461). 



Size. Fully grown specimens of different species range up to at least seven to eight 

 feet (p. 459) in breadth and perhaps somewhat larger. They have been credited with 

 weighing up to 800 pounds, and Eagle Rays are much heavier than dasyatid Rays of 

 equal dimensions because of the greater thickness of their pectorals. However, we 

 suspect that estimated weights of large specimens are apt to be considerably exaggerated, 

 since these Rays are awkward to handle because of their shape. 



Development. It has been known for many years that Eagle Rays are ovoviviparous. 

 As in the Dasyatidae, the embryos are nourished by a creamy fluid secreted by vascular 



1. On the dorsal surface in the Dasyatidae, Urolophidae, and Gymnuridae. 



2. For illustrations of the pelvis, see Fig. 79. 



