EPHEMERID/E OF OTHER RIVERS. 15 



The genus Potomantlius is represented in Great Britain by 

 the single species P.luteus. This fly is not often seen in th* 

 day-time, as it prefers to be on the move after dark. The dun 

 is large and of a distinct yellowish tint all over. The spinners 

 of both sexes have a narrow yellow margin to the wings, other- 

 wise they are not unlike the Sherry spinners. 



Habrophlebia fusca is a small fly. The wings of the dun 

 are light grey the sort of grey which is made by mixing pure 

 white and black without any blue in it. Neuration : whitish. 

 The thorax is pitch brown all over with a few pale markings 

 between the wings. 



The male imago has intense burnt-umber-brown eyes and 

 jet black thorax. The abdomen is dark reddish brown 

 throughout. The hind wing has a very marked angle towards 

 the centre of the upper margin, unlike any other British genus. 

 The female spinner is very like the male. 



The genus Canis is the last of the three-prongers , and is 

 represented by four species. Some of them are very minute 

 forms, and all are further distinguished by the fact that the 

 hind-wings are absent. This is the only genus with two wings 

 and three setae. 



Mr. Halford tells us that he has never discovered Ccenis in an 

 autopsy, and that it is not acceptable to the fish. At the same 

 time it must be admitted that this opinion is not universally 

 held. It is certain that Ccenis sometimes appears in vast 

 swarms, and that this appearance often coincides with a violent 

 rising of the fish, particularly on certain lakes, for example 

 Eavensthorpe in Xorthants. At such times the fish are 

 unusually difficult to hook, and it will generally be found that 

 those fishers, who insist that trout go mad on Ccenis, are free 

 to admit that they had never been able to put the matter 

 beyond dispute by killing a fish with the goods on him. So we 

 must leave it at that for the present. 



We may begin the list of two-prong ers with a fly well known 

 to dry and wet-fly man alike The March Brown. Strictly 

 speaking this name should only be applied to Ecdyurus venosus, 



