RAYS. 43 



range, but are commonest in the temperate seas, and are more 

 numerous in the northern than in the southern hemisphere. The 

 British species are : — Thornback, Raia clavata, 109 ; Homelyn 

 Ray, R. maculata ; Starry Ray, R. radiata ; Sandy Ray, R. circu- 

 laris, 115 ; Common Skate, R. batis, 112 ; Burton Skate, 

 R. marginata t^see specimen 10/9 on the floor beneath the tail of 

 the skeleton of the Basking Shark, within the mahogany rail in 

 the middle of the Gallery) ; Shagreen Ray, R. fullonica ; Flapper 

 Skate, R. macrorhynchvs ; Sharp-nosed Skate, R. oxyrhynchus, 

 111 ; Owl Ray, R. microcellata. Some of the Skates attain to a 

 considerable size, the disc of large specimens measuring six or 

 seven feet across. All of the species of Raia are marketable fish. 

 The genus dates back to the Upper Cretaceous. 



The Thornback, Raia clavata, 109, has, in addition to the small 

 asperities of the skin, large, curved spines, with very large 

 embedded bases, arranged on the back and tail (see 110). The 

 specimen of the Common Skate, Raia batis, 112, mounted to 

 present its under surface, shows well the paleness of the skin as 

 contrasted with the colouring of the skin of the upper surface 

 (compare with the Sharp-nosed Skate, 111) ; it also shows the 

 mouth as a transverse cleft, set at some distance from the front of 

 the disc, and the five pairs of gill-slits arranged symmetrically 

 near the middle of the under side of the disc. The eyes and 

 spiracles of Skates are on the upper surface (see 111). The eggs 

 of Skates are pillow-shaped, with a process at each of the four 

 corners; in colour they are brown or black. Empty egg-shells 

 are often to be seen on the beach after a storm (see 114). 



In the Myliobatidae, a family which includes the Eagle Rays and Eagle 

 Sea-devils or Devil-fishes, the pectoral fins are of very large size ; ays * 

 they are interrupted at the sides of the head, but reappear as either 

 one or two small cephalic fins at the front of the snout. The tail 

 is very slender; the cleft of the mouth is straight, and the 

 dentition is in the form of a triturating mosaic-work or pavement, 

 in some cases strongly arched in an antero-posterior direction. 

 The various species of Dicerobatis, the Devil-fishes, are the largest Devil- 

 of the Rays ; some specimens measure 15 feet across, and weigh ^ s ^- 

 over 1000 lbs. A specimen of Dicerobatis eregoodoo measuring 

 9 feet across is suspended from the roof between Wall-cases 6 and 



