586 NOTONECTINA. 



the fold ; Emlolinm narrow, nearly as long as the corium. Wings 

 very delicate, the nerves forming 4 cells, the 1 st 2 near the anterior 

 margin, one before the other, between thq 1st and 2nd nerves, whicli 

 project a little beyond the 2nd cell; the 3rd and 4th long, sub- 

 parallel, the 2nd emitting a short nerve at the end. Sternum long, 

 with large cavities for the coxse ; the sides densely clothed with long 

 appressed hairs ; Prostermim short, sides deflected ; Ilesosternum 

 oblong, subparallel, xyphus subcordate ; Metasternum in length and 

 form similar to the mesosternum, Lef/s ; coxcb large, 1st and 2nd 

 pairs inwardly concave, 3rd pair cylindrical, horizontal ; fulcra large, 

 tlie 2ud pair fitted into the base of the thighs ; tldglis ; 1st and 2nd 

 pairs broad at the base, gradually less downwards, the 2ad beneath, 

 with a strong spine before the apex ; 3rd pair long-fusiform, thinner, 

 compressed, the underside with a channel throughout ; tibice ; 1st 

 and 2nd pairs compressed, broad, narrowed at the base ; subtrigonate, 

 curved, beneath with a longitudinal channel ; 3rd pair thinner, longer, 

 ciliated within ; iarsi 2-jointed ; 1st joint more than twice as long as 

 the 2ud; 1st and 2nd pairs stout, rounded above, flat beneath; 3rd 

 pair slender, nearly as long as the tibia, ciliated within ; claws ; 2 on 

 each tarsvis, on the last pair very short. 



Abdomen long oval ; above, the basal segments convex, the pos- 

 terior compressed, angulated ; beneath raised angularly in the middle 

 into a keel which is ciliated, the sides sloping into a deep groove 

 within the connexivum, which, narrow above, ia broad and flat 

 beneath, and internally fringed with long hairs. The 1st segment, 

 beneath, is anchylosed with the 2nd, but above is distinctly visible ; 

 the 4th segment in both sexes, on its posterior margin, is deeply, 

 angularly excised, and in the $ the last 2 segments also, but in a 

 less degree; in the $ the last 2 segments are straight. Genital 

 segments in ^ and ? outwardly much alike. In the $ the 2nd is 

 the largest, it follows the last abdominal segment, and is formed like 

 it; it consists of 4 connected pieces — 1 upper, 1 under, and 2 

 lateral. The under plate is large, long, hindwardly pointed, nearly 

 triangular, separated from the side plates by a deep incision, reaching 

 almost to its base, and is thus slightly movable. The convex upper 

 plate is broadly excised on its hinder margin, and here, only on the 

 upper side, is seen the 3rd segment, consisting of 1 thin convex 

 plate, deeply, angularly excised on its posterior margin; on tlie 

 underside it appears as 2 stout, horny, almost triangular plates, 

 whose inner angles meet in the centre, which is covered by the 

 under plates of the 2ud segment. On the inner angle of the plates 



