flydrometride. 151 
pale spots, which, with the margin, are clothed with shining 
silvery pubescence; dise with an elevated dorsal line ; 
elytra greyish black, with numerous elongate white patches, 
and a round one behind the centre of the lateral margin ; 
abdomen black, with silvery patches of hair above, and 
clothed beneath with silvery hairs; legs black, femora pale 
at the base. 
L. 1-14 mm. 
Macropterous form rare; near Chobham; Reigate ; 
Lincolnshire, J. H. Muson ; Norfolk, “ common,’ Hdwards ; 
Cardiff and Taff’s Well, Billups; Pett Level, Sussex, 
Butler ; Hayling, Lulworth, Edinburgh, Belfast, Dale. 
GERRIDINA. 
GERRIS, /uab. 
A genus distinguishable at once by its long thin legs, and 
its habit of jumping along the surface of the water. 
Species often dimorphous, elongate, upper surface dull, 
more or less black, in some species with the pronotum 
brownish, beneath densely clothed with brilliant silvery 
hairs. Head short; face horizontal, parallel-sided in front 
of the eyes; eyes very large and prominent; ocelli none; 
antenniferous tubercles small, but slightly prominent ; 
antenna: with the first joint very long; rostrum short; first 
and second joints short and thick, fourth joint thin ; pro- 
notum elongate, constricted anteriorly, its base produced 
into a somewhat rounded angular process; elytra, when 
present, hard, coriaceous, strongly ribbed; connexivum 
sometimes produced at the apex into an acute process, at 
other times into a rounded angle; three genital segments 
visible in the 3, two in the 9; anterior coxe very distant 
from the intermediate pair; intermediate and posterior 
pairs close together, situated on the sides of the sterna; 
