436 Memoir Sears Foundation for Marine Research 



edge of transverse curtain on roof of mouth straight, coarsely fringed; free anterior 

 margin of fold overlapping youngest row of teeth is bordered with a band of short blunt 

 knobs but without papillae farther back; floor of mouth with 5-6 slender papillae. 

 Teeth in seven series above and below, those of successive rows closely apposed but not 

 overlapping, forming a single dental plate in each jaw; upper dental plate strongly 

 bowed downward anteriorly, but the lower nearly straight from front to rear; the median 

 series of teeth broader than the lateral series. Skin, apart from tail spines, smooth or 

 with a tubercle over the eye, or with a few low tubercles in midline of back, also on 

 shoulder region in males. Subrostral fin connected with main portions of pectorals by a 

 continuous series of radial cartilages along each side of head; those supporting main 

 portion of pectorals little if any stouter than those of subrostral fin. Pelvis strongly 

 arched, with a long slender median process directed forward. Anterior and posterior 

 surfaces of gill arches, inward from gill filaments, each with a longitudinal series of low 

 rounded fleshy knobs, widely spaced. Characters otherwise those of the family. 



Size and Development. The larger species grow to a width of at least four feet, 

 perhaps wider, and to a length of 15 feet or more including the tail. 



Development is ovoviviparous, and the uterus is described as lined with villi,* as 

 it is in the Sting and Butterfly Rays and in other Eagle Rays (pp. 337, 397, 433). 



Habits. The true Eagle Rays seem to fly through the water rather than swim in 

 the conventional sense of the word, doing so both gracefully and fairly rapidly. "On 

 occasions they will break the surface of the sea and skim for a short distance through 

 the air. When captured, they are unpleasant customers to handle, lashing about in all 

 directions with the flexible tail and trying to bring the saw-edged spine into action."* 

 One kept in an aquarium was described as grunting rather loudly whenever it was taken 

 out of the water.i" 



The presence of Eagle Rays of this genus in the vicinity of offlying islands, such 

 as Madagascar and Reunion in the Indian Ocean and the Canaries and Azores in the 

 Atlantic, and their reported capture 320 miles off Plymouth, England," is evidence that 

 they may carry out journeys of considerable length across the open sea. But they are 

 most often encountered in coastal waters. Within their centers of abundance they occur 

 commonly in shallow bays and estuarine situations over sand and mud flats. 



Although a species of Myliobatis has been reported from an Argentine lagoon that 

 is connected with the sea by only a narrow canal, ^^ inclusion of the genus in lists of 

 freshwater fishes" seems premature; so far as we can learn, this leads back to a spec- 

 imen from Rio de la Plata," which seems likely to have been taken in the vicinity of 

 Buenos Aires (having been received by the British Museum from a correspondent in 

 that city) and hence from salt water. 



8. Alcock, J. Asiat. Soc. Beng., sg (2), 1890: 51; Alcock and Wood-Mason, Proc. roy. Soc. Lond., 50, 1891: 20a; 

 Gudger, Proc. biol. Soc. Wash., 26, 1913: loi. 



9. Norman and Fraser, Giant Fishes, 1937: 77. 10. Moreau, Poiss. France, i, 1881: 446. 



11. Jenkins, Fish. Brit. Isles, 1925: 342. 



12. McDonagh (Rev. Mus. La Plata, 34, 1934: 95, footnote i), as M. aquila. 



13. As by Eigenmann (Rep. Princeton Exped. Patagonia, j [i], 1909: 348; 3 [2], 1909: 378) and by Smith (Biol. Rev. 

 [Cambridge], 11, 1936: 65). 14. Gunther, Ann. Mag. nat. Hist., (5) 6, 1880: 8. 



