186S.] 



80 



Genus B.iiTiscA, Walsh. 

 Syn. Baetis, part., Say. 

 Type B. ohesa, Say. 

 Distrib. — United States. 



The anterior ulnar rib is seemingly tri-partite. (The anterior di- 

 vision is probably a supplementary vein, which, with its foremost parti- 

 tion, is bipartite, and includes a simj^le supplementary vein ; its second 

 division is simple). The second partition of the first ulnar rib is bifurcate, 

 and includes a simple supplementary vein : its third partition is simple. 

 The simple posterior ulnar rib is succeeded by two supplementary ribs, 

 the hinder of which sends several simple veinlets, parallel one with 

 another, to the internal margin. There are two straight, simple, vasa 

 interna. The forceps of the ^ seem to be 3-jointed, and to have the 

 second joint the longest, as in Ephemerella (but that which appears to 

 be the proximal joining may be a fold in the integument only, in which 

 case the first joint would be by far the longest, and would present an 

 obtuse spine on its under-surface, like the first joint of the forceps of 

 some species oi Leptophlehid). A jointless remnant of the central seta 

 is retained. 



Genus Colobueus,* nov. gen. 

 Syn. Palingenia, Burm., part., Walker. 

 Type G. humeralis, Walker. 

 Distrib. — New Zealand. 



The vas uliiare resembles somewhat that of the preceding genus in 

 its manner of branching. It is followed by two supplementary ribs, 

 and two supplementary veins. The first of these ribs sends down three 

 or four bent, simple (or slightly bifurcate), veins to the internal 

 margin ; the second of them resembles a vas internum. There are 

 about four, slightly curved, vasa interna, some simple, others bifurcate, 

 or even bifid. The outer setae are upwards of fifteen times longer than 

 the central one. The J has 4i-jointed forceps, their second joints are 

 the longest ; eyes double. 



Genus Siphlonueus,! nov. gen. 

 Syn. Baetis J Ed. Pict., part. 



Ephemera, Zett., part. 

 Type S.Jlavidus, Ed. Pict. 



Distrib.— Sweden, England, Ireland, Spain, 1 sp. ; Prussia, 2 sp. ; 

 United States. 



* Kolobourot (Or.) = stump-tailed. 



+ Sip hie our a (Gr.) = defective in the tail. 



