284 SALT-WATER FISHES 



to believe that the fish is not upside down. The disc is flat 

 and oval, with a dozen or more transverse plates, and acts 

 by vacuum. Remoras attach themselves to many large fishes 

 and cetaceans, but chiefly to sharks and rays, possibly because 

 their rougher granulated skins give a better hold. In 

 tropical seas it is not unusual to see enormous rays hurling 

 themselves out of the water in order to shake ofF these remoras, 

 which evidently irritate them. Perhaps the most interesting 

 occurrence of the remora in our seas was that of a head and 

 shoulders found, during the Irish survey (i 890-1), in the 

 stomach of a picked dog-fish {Acanthias)* for the episode 

 clearly shows that elasmobranchs prey on these parasites. 



The Flying-fish {Exocatus volitans) is doubtfully included, 

 with a second species, in Day's British Fishes, but the 

 evidence of their presence alive on our coasts is too unreliable 

 to make a detailed description desirable. 



Centrolophus britannicus and C. pompilus, the latter known 

 as the " Black-fish," the former apparently without vernacular 

 name, are two rare visitors from the Atlantic. Couch says 

 that an example of the former was thrown ashore near Looe in 

 1859, and that is the only recorded British occurrence. The 

 second species has been taken on several occasions, the first 

 on record also coming from the neighbourhood of Looe. It is 

 said to follow sharks. Day enumerates some seventeen cases 

 of its capture in our seas, and a recent occurrence is mentioned 

 by Holt, who says that six or eight were taken in a mackerel 

 boat off^ the Runnstone, near the Scilly Islands. These were 

 evidently young examples, for they measured only 12 or 

 13 in. They had been feeding on small pollack of 3 in. In 



* See Holt and Calderwood, Trans. Hoy. Dub. Soc, September, 

 189S, p. 413. 



