108 



537. The tail of an Eagle Ray (Myliobates], showing a series of five serrated spines 



in succession. The tail measures 7 feet 8 inches in length, from the base of 

 the first spine. Hunterian. 



538. The tail of a smaller Myliobates, showing two, fractured, serrated spines. 



Hunterian. 



539. Part of the tail of another species of Myliobates, with a single and longer ser- 



rated spine. The skin of the tail is granulated with small placoid tubercles. 



Hunterian. 



540. The caudal serrated spine, apparently, of a Myliobates. Hunterian. 



541. A portion of the dental pavement of a lower jaw of a true Myliobates: this 



subgenus is characterized by one broad middle series, and by several narrow 

 lateral series of denticles. Hunterian. 



542. The upper and lower jaws of a small specimen of a Myliobates, with the dental 



plates. 



The upper series of plates is convex, both transversely and longitudinally, but more so in 

 the latter direction : the plates of the lower series are narrower and are nearly horizontal. 

 Its anterior extremity projects beyond the jaw, and can be used like a spade in digging out 

 shell-fish, crustaceans, &c., from the sandy bottoms frequented by these Rays. 



Hunterian. 



543. A portion of the dental covering of the upper jaw of an Eagle Ray (Zygobatcs). 



Mm. Brit. 



544. A portion of the upper jaw with the dental pavement of a Zygobates. 



Hunterian. 



545. A portion of the upper jaw, with its dental pavement, of a Zyffobates. 



This genus is characterized by the great breadth of the series of teeth on each side the 

 middle series. The outer rows, two or three in number, are composed of small prismatic 

 teeth. There are two rows on the right and three on the left of the present specimen. 



Hunterian. 



