172 NATURAL SCIENCE. March, 



America and Europe," published in the Report of the United States 

 Commission of Fish and Fisheries for 1886, although, so far as relates 

 to British species, I can speak from my own observations. 



Zeugoptcrus is a fairly well-marked genus, with a very limited 

 distribution. Its definition is to some extent a matter of opinion, 

 different ichthyologists classifying the species differently. It is, how- 

 ever, agreed that there are three species that all possess the following 

 characters : a large foramen in the septum between the gill-cavities ; 

 the posterior extremities of the dorsal and ventral fins prolonged on to 

 the lower right side of the body beneath the base of the tail ; the scales 

 on the upper surface ctenoid, having a single row of spines, of which 

 the central one is prolonged ; the shape of the body approaching the 

 rectangular. The three species are definitely distinguished from one 

 another by the following single characters : in Z. unimaculatus, Risso, 

 the first ray of the dorsal fin is produced into a filament ; in 

 Z. piinciatus, Bloch, the pelvic fins are concresced with the ventral 

 (or anal) ; in Z. novvegicns, Giinther, neither of these characters is 

 present. 



As to distribution, no species having the foregoing characters has 

 been found anywhere except on the coasts of Europe, and all three 

 species occur on the British coasts. Z. punctatus is fairly common 

 near Plymouth, and occurs all along the south and east coasts of 

 England. It has been taken on the east coast of Scotland as far 

 north as the Orkneys, on the west coast in the Firth of Clyde, also 

 on the east coast of Ireland. Northward the species extends to the 

 north coast of Norway, southward to the northern shores of France, 

 but it is absent from the Mediterranean. Z. novvegicns is also a 

 northern form absent from the Mediterranean. I have taken several 

 specimens at Plymouth ; one specimen has been taken on the west 

 coast of Ireland, and three specimens in the Clyde. It is somewhat 

 rare on the Scandinavian coasts. Z. unimaculatus, on the other hand, 

 is a Mediterranean form, only occasionally taken on British and 

 northern coasts. I have never obtained a specimen at Plymouth. 

 On the south-west coast of Scotland it is more abundant than at any 

 other part of the British coast, several specimens having been taken in 

 Loch Fyne and the Firth of Clyde. It has been taken on the coast 

 of Denmark, but not on the coast of Norway. 



Steenstrup is the only ichthyologist who has placed these species 

 in the same genus, Zeugopterus, and he included with them the whiff 

 or megrim, Z. megastoma, because it too has the perforation in the 

 septum of the gill-cavity. The three species have been separated by 

 Giinther and others according to the presence or absence of teeth on 

 the vomer, and the union of the pelvic with the ventral fin, or its 

 separation therefrom. But the three species are so similar in their 

 general character, and are united by such salient features, that it is 

 clear they have recently diverged from a common parentage. 



We have certain direct observations on the habits of these fishes 



