io6 SALT-WATER FISHES 



The Common, or Grey, Skate {Rata batis) is a pale grey 

 species with black spots ; the under surflice is nearly white and 

 is speckled with black. It has two spineless dorsal fins on the 

 tail, as well as three rows of thorn-like tubercles. It feeds on 

 both fishes and crustaceans, and deposits its purses in early 

 summer. Large examples of this skate are sometimes taken 

 on our coasts, and one of 224 lb. has, in fact, been caught on 

 the Irish coast. 



The Thornback (i?. clavatd) will better serve as a typical 

 ray, and it has been more studied and observed than the last. 

 The vernacular name of this species is not particularly happy, 

 as, with one exception, all rays have some equipment of spines 

 and tubercles on the upper surface, and the present species is 

 even less formidably covered than the Starry Ray. In general 

 colouring, and allowing for the aforenamed variation, the 

 thornback is dark and mottled on the upper surface and white 

 beneath. Abnormally coloured thornbacks are, however, not 

 very rare, and one was figured and described some years ago 

 by Professor Traquair.* In his example, the upper side 

 was white and had blotches of dark grey and small black 

 spots. On the under side the colouring was normal. Dr. 

 Traquair regarded this as a case of partial albinism, but 

 his conclusion that such colouring could not afford protection 

 against any known kind of sea-bed is hardly supported by 

 a reference to his figure. The spiny growths on this 

 species are mostly confined to a single row down the middle 

 of the back and continuing to the tail, and four other 

 patches, one at each extremity of the wings and one on either 

 side of the back of the head. There may also be a few close 

 to the eyes. 



The thornback inhabits moderately shallow water, and is 



often hooked in less than 8 fathoms on the inshore grounds 



of Cornwall. There is an idea in that part of the country that 



this ray, instead of passing most of its life at the bottom like 



* Annals of Scottish Natural History, January, 1893. 



