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 fin 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 genus Aetobatis, now represented by a single 
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 
Other Genera. 
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 Gephaloptera , 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 
