72 GIANT FISHES 



folds along the sides of the tail seen in the Guitar-fishes, 

 Electric Rays and True Rays are usually absent, but there 

 are often folds or keels along the upper and lower surfaces. 

 There is sometimes a single small dorsal fin placed near the 

 root of the tail, and a caudal fin may also be present. The 

 pectoral fins extend to the extremity of the snout, which is 

 actually supported by the union of these fins in front of the 

 skull, which has no rostral cartilage. The pelvic fins have no 

 notch. There is nearly always i (sometimes 2 or more) 

 saw-edged spine on the back of the tail. The skin of the 

 upper surface is either smooth or roughened with tubercles. 

 There are no hooked spines at the edges of the pectoral fins 

 in the males, and the two sexes are alike apart from the 

 claspers. 



These rays are found in most warm seas. Some of the 

 species enter rivers, and others live entirely in fresh water. 

 Fossil remains date back to the Cretaceous period. 



WHIP-TAILED STING RAYS. 



(Genus Trygon.) Fig. 29 a. 



The tail is long and whip-like, without either dorsal or 

 caudal fins. The mouth forms a straight or more or less 

 curved slit on the under-side of the head, and the jaws are 

 armed with several rows of small teeth set in pavement 

 fashion. The spiracles are large and placed close behind the 

 eyes. The coloration is variable. 



Some of the larger species grow to a width of 5 or 6 feet 

 across the disc. 



There are about 30 species of these Sting Rays, and among 

 the larger forms the following may be mentioned. The 

 Common Sting Ray (T. pastinaca), from the Mediterranean 

 and eastern Atlantic ; the Stingaree or Clam-cracker (T. 

 centrums), from the Atlantic coast of North America ; the 

 Southern Sting Ray (T. sayi), ranging from Carolina to 

 Brazil ; the Fan-tailed Ray (T. sephen), from the Indian and 

 Pacific Oceans ; and the Crack- whip Ray (7\ uarnak), with a 

 similar distribution. The first of these makes its appearance 

 on the British coasts with some degree of regularity every 



