Revision of the Notonectidx. 397 
posterior femora extending beyond the apex of the 
hemielytra; to which they do not attain in the other 
genera. 
Noronecta, L. 
Linn., 1758, Syst. Nat., Hd. x., p. 439; Fieb., 1851, 
Abh. bohm. Ges. Wiss. (5), vil., pp. 205 and 472; 
Flor, 1860, Rhynch. Livl., i., p. 766. 
Typr. WN. glauca, L.; Fabr., 1794, Ent. Syst., iv., 
p. o7. 
Flor has given such a masterly description of the 
genus that it is not necessary here to do more than 
indicate the leading features; to comprehend the exotic 
species it is necessary, however, to modify shghtly Flor’s 
description of the head and eyes. Fieber’s figures (J. c., 
pl. ., D) are admirable except that the pronotum is 
too long in proportion to its breadth, the posterior pedes 
are represented with long unguiculi, of which they are 
really devoid, and the alar neuration is not quite correct 
in its proportions. 
To the characters given previously, it may be added 
that the intermediate ambulacra are not nearly con- 
tiguous (as they are in Hnithares) and the posterior 
ambulacra are practically contiguous, distinguishing the 
genus at once from Anisops; the median ventral carina 
of the abdomen is thickly pilose, as are the lateral 
margins, thus forming a waterproof covered way over 
the ‘‘ gutters,” which lie, one on each side of the carina, 
for the conveyance of air. The junctures of the con- 
nexival ventral segments are always covered with short 
thick hair, and the scutellum and hemielytra are generally 
clothed with short golden yellow pubescence. ‘lhe sexes 
are almost indistinguishable in size, form, colour and 
general appearance, though, of course, the female, when 
full of mature ova, is dilated more than at other times. 
They can be very readily separated by an examination of 
the last three or four abdominal ventral segments. ‘hese 
ave horizontal in the female, rounded and anteriorly 
excavated in the male. 
Notonecta is a genus of which the species are singu- 
larly lacking in specific characters suitable for diagnosis : 
and the analytical table has been based principally upon 
the structure of the notocephalon and pronotum. With 
TRANS. ENT. SOC. LOND. 1897.—parT Iv. (DEC.) 27 
