32 THE EAYS. FAMILY RAIID.E. 



into numerous families. The first of these groups is the tribe 

 of the Rays (Raiina\ including six families ; whilst the second 

 tribe, that of the Sharks (Squalina), includes no less than ten 

 families. It will, however, only be necessary to allude particu- 

 larly to the more important of these numerous families. 



580. The Rays usually have the body so flattened, that the 

 pectoral fins seem like a continuation of it; and these meet in 

 front of the snout, and are prolonged backwards as far as the 

 ventral fins ; thus giving to the whole body a nearly circular 

 form. The eyes are situated on the upper side of the body, as 

 in the ordinary Flat-fish ( 551); but it will be observed that 

 the plan of construction of the Rays and Skates is entirely dif- 

 ferent from theirs, the two margins being here composed of the 

 edges of the pectoral fins, whilst in the Flat-fish they are formed 

 by the dorsal and anal ; and the Flat-fish habitually lying on 

 one side, whilst the Rays lie on the abdominal surface, where 

 we find their mouth and gill-openings. The position of the 

 latter on the ventral surface is, in fact, the most characteristic 

 distinction between these Fishes and the Sharks, in which the 

 branchial apertures are placed on the sides of the body. The 

 body is terminated by a long slender tail, which bears all the 

 perpendicular fins (dorsal, anal, and caudal), but the caudal is 

 sometimes wanting. These Fish live for the most part near the 

 bottom of the water, on beds of sand or mud. When disturbed, 

 they glide along in an undulating manner, with a slight motion 

 of the pectoral fins ; and if attacked, they defend themselves by 

 lashing violently witli the tail, which is often armed with sharp 

 spines. They are all oviparous. In their habits they are ex- 

 ceedingly voracious, feeding on fishes and Crustacea, and on naked 

 or testaceous molluscous animals. The teeth are flattened and 

 lozenge-shaped, forming a sort of mosaic ; and so powerful are 

 the jaws, that they are capable of crushing the shell of a Crab 

 with the greatest ease. 



581. In the RAIID^E, or True Rays, the body is of a lozenge 

 shape, with the snout pointed, and the pectoral fins forming 

 rounded angles. The tail bears two small dorsal fins. This 

 family includes all the best-known species of Rays, and several 



