466 



FISHES 



CHAP. 



an enormous size, and are among the largest of Fishes. 

 Ceratoptera vampyrus of the West Indies, for example, grows to 

 a width of 20 feet, and an embryo extracted from the oviduct 

 of a gravid female 15 feet wide, and from 3 to 4 feet in thick- 

 ness, measured 5 feet across the disc and weighed twenty 

 pounds. 1 This Fish is much dreaded by the divers engaged in 



FIG. 266. The Eagle-Ray, Myliobatis aquila. 



the pearl fisheries near Panama, whom it is said to devour after 

 enveloping them with its vast wings. 2 



The family is exclusively Tertiary, and with the exception 

 of an extinct genus, Promyliobatis, from the Eocene of Monte 

 Bolca, all the fossil species belong to the existing genera 

 Myliobatis, Rhinoptera, and Aetobatis. 



Order V. Holocephali. 



The propriety of including the Holocephali in the sub-class 

 Elasmobranchii is scarcely open to doubt. Like the Acanthodei 



1 Giinther, op. tit. p. 348. 

 2 Dumeril, quoted by Jordan and Evermann, op. cit. p. 92. 



