544 SHARKS AND RAYS. 



occasionally visiting the British coasts, where it is often termed the whip-ray. 

 In this group the head is free from the disc, and the tin on the muzzle single. 

 The large, flat, hexagonal teeth form a tesselated pavement, highly convex in the 

 upper, but flat in the lower jaw; the individual teeth are arranged in seven 

 longitudinal rows, those of the unpaired middle row being much elongated and 

 transverse, while the others form less irregular hexagons. The whip-like tail, in 

 addition to a dorsal fin near the root, is generally armed with a large barbed spine 

 about the middle of its length. In the young the middle row of teeth are not 

 larger than the lateral ones, and their relative width continues to increase 

 throughout life. The species above named, which has an almost cosmopolitan 

 distribution, may attain to a length of upwards of 15 feet, with a weight of about 

 800 lbs. When captured, these rays lash out with their tails, and thus inflict 

 severe wounds with the spine. Fossil species of this genus occur through most of 

 the Tertiary strata ; and among these one from the Eocene of Egypt is remarkable 

 for its enormous size, the teeth of the middle row being rather more than 5 inches 

 in width. Although it is difficult to form an estimate of the exact size of the fish 

 to which these teeth belonged, it is thought that the width of the disc must have 

 been about 15 feet. 



In the allied ^enus Aetobatis, now represented by a single 

 Other Genera. te . . - 



widely-spread tropical species but common in the Tertiary forma- 

 tions, the muzzle carries two fins, and the dentition comprises only a single series 

 of transversely elongated teeth, corresponding to the central row of the typical 

 genus. In a third genus (Rhinoptera), of which there are seven living and several 

 Tertiary species, the so-called fins on the muzzle are likewise double, while the 

 tesselated teeth form five or more series. Of these the middle one is the largest, 

 the first, or first and second, lateral series somewhat narrow, and the remainder in 

 the form of more or less nearly regular hexagons ; the dental plates of both jaws 

 being strongly arched from back to front. The largest existing members of the 

 family belong to the genera Dicerobatis and Cephaloptera, which are mainly 

 confined to the tropical seas, and to which the name of devil-fish might well be 

 restricted. In the former of these the pectoral fins do not extend on to the sides 

 of the head, which is truncated in front, and furnished with a pair of forwardly- 

 directed appendages containing fin-rays, the nostrils being widely separated. 

 Both jaws contain numerous rows of flat or tuberculated teeth ; and the whip- 

 like tail has a single dorsal fin above and between the pelvic pair, and may be 

 armed with a spine. In the second genus, the mouth is terminal, and teeth are 

 present only in the lower jaw. One of the Indian representatives of the first 

 genus is known to measure fully 18 feet across the' disc, and a weight of over 

 1200 lbs. has been recorded. Sir W. Elliot states that the horn-like appendages 

 " are used by the animal to draw its prey into its mouth, which opens like a huge 

 cavern between them. The fishermen [in India] say they see these creatures 

 swimming slowly along with their mouths open, and flapping these great sails 

 inwards, drawing in the smaller crustaceans on which they feed." The capture 

 of such hideous monsters is a work of no little difficulty and danger, as they are 

 quite capable of overturning a boat ; and the danger is said to be the greatest in 

 the case of a female accompanied by its single offspring. We must not leave this 



