Fishes of the Western NortJi Atlantic 459 



of the pelvics and appear to be fully formed on another only 748 mm wide, from 

 Pacific Panama. 



When it reaches full growth, this is one of the larger Rays. The few adults measured 

 have included five that were more than six feet'" wide and two or three others that were 

 more than seven feet wide, the largest being a female 7 feet 7 inches wide. 



Their thick bodies make Spotted Duck-billed Rays heavier than either the dasyatids 

 or the Butterfly Rays at corresponding sizes. Recorded weights are 1 1 1/2 pounds at a 

 breadth of 28 1/2 inches, 58 pounds at a breadth of about three feet," 90 pounds at 

 five feet, 120 pounds at 5 feet 2 inches, and 132 pounds at a breadth of 5 feet 9 inches, 

 with estimated weights of 400—500 pounds for specimens 6 feet 1 1 inches, 7 feet 2 

 inches, and 7 feet 7 inches wide and about 20 inches thick. '^ 



Developmental Stages. The unborn young of this Ray seem to have been reported 

 first in I 87 1." Presumably they are nourished (after absorption of the yolk sac) by the 

 secretions of the villi with which the uterine wall is clothed,'* as in the case of the young 

 of various other Rays (pp. 337, 397, 433)- 



Embryos that have attained a width of 160—170 mm resemble their parents closely 

 in general appearance, except that their tails, already armed with spines, are about 4.5 

 times as long as the body from cloaca to front of subrostral fin and are threadlike toward 

 the tip, their subrostral fins are relatively somewhat shorter, and their eyes and spiracles 

 are somewhat larger. Embryos of this size do not show any indication of the future color 

 pattern, although the outer parts of the disc are already white-spotted on one 250 mm 

 wide which was apparently nearly ready for birth. For an account of the embryonic 

 teeth, see p. 457. 



The unborn embryos lie rolled up lengthwise in the uterus much as in the But- 

 terfly Rays (p. 398). Four to a litter appears to be about the usual number. It is reported 

 by an eye witness that "in giving birth to its young, the female ray leaps high in the 

 air."" But it is not known whether leaping is either necessary or usual in successful 

 parturition. 



Habits. Spotted Duck-billed Rays are said'* to occur singly, in pairs, or in schools 

 of several hundred individuals. They are such powerful swimmers that one 5 feet 2 inches 

 wide, taken at Key West, Florida, dragged a 22-foot launch with engine, propeller, and 

 three men "wherever it wished."" 



They have often been seen leaping clear of the water and, like some other Rays, 



70. One 5 feet 8 inches across and another 5 feet 9 inches, measuring respectively about 9 feet 10 inches and 10 feet 

 from snout to tip of tail, are reported to us from Key West, Florida, by Lt. Comm. C. Saunders, U. S. N. R. 



71. The weight of another of 37 inches is recorded merely as "over 25 pounds, the limit" of the balance used (Gudger, 

 Proc. biol. Soc. Wash., 2$, 1912: 151). 



72. Gudger, Pap. Tortugas Lab., 6 (12), Publ. Carneg. Instn., 183, 1914: 255. 



73. By Klunzinger, Verh. zool.-bot. Ges. Wien, zi, 1871: 686; Red Sea. 



74. These were first described in 1846 by Cuvier and Duvernay (Lemons d'Anat. Comp., 1846: 92) and more recently 

 by Coles (BuU. Amer. Mus. nat. Hist., 32, 1913: 32). 



75. Coles, Bull. Amer. Mus. nat. Hist., 32 (2), 191 3: 30. 



76. We have no firsthand information to contribute on their habits. 



77. Gudger, Aust. Mus. Mag., 6, 1937: 208. 



