DOLPHINS. 453 



wide. A single dorsal extending from the occiput almost to the 

 caudal, which is deeply forked; no distinct dorsal and anal 

 spines. The ventrals are well developed, and can be received in 

 a groove on the abdomen. Scales very small. Rasp -like teeth 

 in the jaws, on the vomer and the palatine bones. Air-bladder 

 absent. 



Generally, thongh by misapplication of the name, called 

 " Dolphins." About six species are known, each of which is 



Fig. 20-2.— Dolplim from the Atlantic. 



probably distributed over all the tropical and sub-tropical 

 seas. Strictly pelagic in their habits, they are most powerful 

 swimmers ; they congregate in shoals, and pursne nnceasingiy 

 the riying-Fish, which try to escape their enemies by long 

 flying leaps. They attain to a length of six feet, and are eagerly 

 caught by sailors on account of their well-flavoured flesh. 

 The beauty of their, unfortunately fugitive, colours has ever 

 been a subject of admiration. As far as the colours are 

 capable of description, those of the common species [C. hip- 

 purus), which is often seen in the Mediterranean, are silvery 

 blue above, with markings of a deeper azure, and reflections 

 of pure gold, the lower parts being lemon-yellow, marked with 

 pale blue. The pectoral fins are partly lead colour, partly 

 yellow ; the anal is yellow, the iris of the eye golden. These 

 iridescent colours change rapidly whilst the fish is dying, as 

 in the Mackerel. The form of the body, and especially of the 

 head, changes considerably with age. Very young specimens, 

 from one to six inches in length, are abundant in the open 

 sea, and frequently obtained in the tow-net. Their body is 

 cylindrical, their head as broad as high, and the eye relatively 



