42 FISH GALLERY. 



of the jaws are minute and obtuse, and merely serve to seize the 

 pieces of flesh left projecting from the body of the animal 

 attacked. 



The endoskeleton of the rostral saw of the Saw-fish consists of 

 a variable number (usually three) of long tapering tubes (see 

 specimen 101), encrusted with granular calcifications similar to 

 those found upon the other cartilages of the skull. One of these 

 tubes, found detached, remained for a long time a puzzle to 

 naturalists, and was even described in 1864 as the arm of a kind 

 of Star-fish, to which the name Myriosteon higginsii was given. 

 Rhino- In the Rhinobatidse, as in the Pristidae, the tail is long and 

 powerful ; it is provided with two large dorsal fins, without spines, 

 and has a longitudinal fold along each side. The caudal fin is well 

 developed. The trunk is not greatly expanded and the head is 

 not embraced by the pectoral fins. The family is represented 

 by well-preserved skeletons in the Lithographic Stone (Upper 

 Jurassic). Of the recent genera, Rhynchobatus and Rhinobatus are 

 the most important. In Rhynchobatus djeddensis (104) the snout 

 is narrower and more pointed than in Rhynchobatus ancylostomus 

 (102), and the calcareous tubercles on the back are smaller ; the 

 undulation of the toothed surface of the jaw is less marked 

 (compare jaws 105 and 103). Rhinobatus (e. g. Rhinobatus granu- 

 latus, 106) differs from Rhynchobatus in having the dorsal fins set 

 farther back, and in the caudal fin having no lower lobe ; the front 

 of the skull is produced into a rostrum, and the space between the 

 side of the rostrum and the front part of the pectoral fin is filled 

 by skin. The teeth are obtuse, with an indistinct transverse ridge 

 (see jaws 107). Rhinobatus yranulatus occurs in the Indian seas ; 

 R. lentiginosus is common off Florida, where it is known as the 

 Guitar-fish. Trygonorhina, 108, is an Australian genus. 

 Skates In the Raiidae (Skates and Rays) the disc is broad, rhombic, 



o 11 ^ and generally with dermal asperities or spines. The pectoral fins 

 extend to the snout. The tail has a longitudinal fold on each side, 

 and does not bear barbed spines such as occur in the Sting Rays 

 ^Wall-case 4). There is a rudimentary electric organ in the tail. 

 In the Thorn back and some other species of Raia the teeth are 

 pointed in the male, but blunt and flattened in the female (see 116 

 and 1 17). The fishes of the genus Raia have a wide geographical 



