320 THE COMMERCIAL SEA FISHES OF 



Habits. The thornback is found in shallower waters 

 than most of the family, and is taken all through the year. 

 Lowe observes that off the Orkneys they are frequently met 

 with in the eddies of the tides, or where two tides meet ; 

 especially when the tides run strong they are obliged to 

 withdraw to these calmer spots, their shape hindering them 

 from sustaining themselves against the force of a strong 

 current. These fish have been observed to glut themselves 

 with scad (Caranx trachurus). 



Means of capture. Trawls and baited hooks ; they are 

 partial to herrings, pilchards, and crabs and other Crustacea. 



As food. It is good eating when not too large, but as in 

 all members of this family it becomes coarse with age. In 

 Ireland it is the form least objected to, but only the young 

 or half-grown are employed as food. In Scotland they are 

 mostly prepared under heavy pressure, as already alluded to. 

 In many places the livers are removed for the purpose of 

 extracting the oil, which is said to be much used by shoe- 

 makers in the preparation of cobbler's wax ; also fish-liver 

 oil is exceedingly useful as an adjunct to the paint of 

 boats. Further remarks on the rays and skates appear 

 to be scarcely necessary. This species is taken all round 

 our coasts. 



SUB-CLASS III.-CYCLOSTOMATA. 

 FAMILY I. LAMPREYS (Petromyzontida). 

 I. The Sea-lamprey (Petromyzon marinus). 



Names. Lampreda, Anglo - Saxon. Lamprey, from 

 " lambere," to lick, and " petra," a stone. In some places 

 termed a " sucking-fish." Nine-eyes and seven-holes. Llys- 

 owen bendoll and Llamprai, Welsh. 



Of an eel-shaped form, with in the adult a circular mouth 





