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.’ This Fish is much dreaded by the divers engaged in 
Fia. 266.—The Eagle-Ray, A/yliobatis aquila. 
the pearl fisheries near Panama, whom it is said to devour arter 
enveloping them with its vast wings.” 
The family is exclusively Tertiary, and with the exception 
of an extinct genus, Promyliobatis, from the Eocene of Monte 
Bolea, all the fossil species belong to the existing genera 
Myliobatis, Rhinoptera, and Aétobatis. 
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. ctt. p. 348. 
2 Duméril, quoted by Jordan and Evermann, oy. cit. p. 92. 
