Fishes. 



6333 



On the Occurrence of the Derbio (Lichia glaucus, Cuv.) in MounVs 

 Bay. By R. Q. Couch, Esq., M.R.C.S., &c. 



The Derbio seems to be a somewhat rare fish, even in the localities 

 in which it is most commonly taken ; but in British waters this is, I 

 believe, its first recognized visit. By the kindness of the fishermen 

 of Mousehole and Newlyn I have generally an opportunity of examining 

 the rare fish captured in the neighbourhood of the Land's End, and 

 from one of them I received the specimen from which the following 

 description is taken. It was captured in a drift-net employed in the 

 ^autumnal mackerel fishery, in deep water, off the Runnel Stone, at the 

 western entrance to Mount's Bay. 



The length of the specimen is 13 inches ; it is deep from the ventral 

 to the dorsal margins, and is very much compressed laterally. The 

 general shape of the body is fusiform, being much contracted at the 

 root of the caudal fin, and the head is small and much pointed ante- 

 riorly. The general colour is dark ; the dorsal surface is of a deep 

 bluish black tint, somewhat similar to the mackerel, but much deeper; 

 this tint terminates somewhat abruptly in a grayish neutral tint above 

 the lateral line ; and this inferiorly gradually fades away into a silvery 

 white, with patches of red and yellow, which disappear soon after 

 death. On the anterior and middle of the sides are traces of five per- 

 pendicular bands, similar to what is observed in the pilot fish ; above 

 they blend into the dark colour of the back ; about the lateral line 

 they are distinct, but below they again fade into the surrounding tints. 

 The lateral line is straight posteriorly, and continues so till it arrives 

 nearly on a plane with the origin of the dorsal fin, when it gradually 

 arches up so as to reach the head above the margin of the gill-covers. 

 The head is small and short ; the jaws, when closed, are sharp or 

 pointed, — lower jaw longest ; the teeth are numerous,- small and ir- 

 regular. The eye is small and bright, irides yellowish red, and 

 situated much interiorly ; moustache smooth. 



The surface of the body is covered by numerous small scales. The 

 head and gill-covers are smooth. 



The caudal fin is large, for the size of the fish, deeply falcate and 

 strong ; the external fin-rays are stout, strong and closely arranged ; 

 the central ones are short and membranous. The dorsal and abdo- 

 minal fins arise nearly opposite to each other and rather posteriorly to 

 the middle of the body. The anterior rays of the dorsal fin are much 



