RAYS. 107 



terranean, it has been found occasionally on the south coast of 

 England. 



The family oiRhinidtB contains only one species, the "Angel-fish ' ' 

 or " Monk-fish " {Rhina squatina) (Case 41), which approaches the 

 Rays as regards form and habits. Within the temperate and tropical 

 zones it is almost cosmopolitan; it does not exceed a length 

 of five feet ; it is viviparous, producing about twenty young at 

 a birth. 



The Pristiophorid(2 (Case 41) resemble so much the common 

 Saw-fishes as to be easily confounded with them, but their gill- 

 openings are lateral, and not inferior. They are also much smaller 

 in size, and a pair of long tentacles are inserted at the lower side 

 of the saw. The four species known occur in the Australian and 

 Japanese seas. 



B. Batoidei : Rays. 

 The true Rays lead a sedentary life, moving slowly on the 

 bottom, rarely ascending to the surface. They progress solely 

 by means of the- pectoral fins, the broad and thin margins of 

 which are set in an undulating motion, identical with that of the 

 dorsal and anal fins of the Pleuronectidne, or Flat-fishes. They 

 are exclusively carnivorous, like the Sharks, but unable to pursue 

 and catch rapidly-moving animals. 



The Saw-fishes, Pristidte (Case 41), agree with the Rays in the 

 position of their branchial clefts. They are abundant in tropical, less 

 so in subtropical seas. They attain to a considerable size, specimens 

 with a saw 6 feet long and 1 foot broad at the base not being of 

 uncommon occurrence. The saw renders them most dangerous to 

 almost all the other large inhabitants of the ocean. Its skeleton con- 

 sists of three, sometimes five, rarely four, hollow cylindrical tubes, 

 placed side by side, tapering towards the end, and incrusted with an 

 osseous deposit, as shown in a preparation in Table-case C. The 

 teeth of the saw are implanted in deep sockets of the hardened in- 

 tegumentj and are, as regards their origin, from dermal papillae, 

 and their mode of attachment a unique structure among Fishes. 

 The teeth proper, with which the jaws are armed, are much too small 

 for inflicting wounds or seizing other animals. Saw-fishes use the 

 saw in tearing pieces of flesh off an animal's body or ripping 

 open its abdomen ; the detached fragments or protruding soft parts 



