DYTISCIDES. 113 



I, Under-side of anterior male tarsi with a large 

 sucker at base, two much smaller ones obliquely 

 l)efore this and a number of small cups. 



Elytra short oval, dilated behind, of female furrowed, 

 furrows hairy; intermediate tarsi simple and posterior tarsi 

 fringed on each side in both sexes. Acilius, Leach. 



II, Under-side of anterior male tarsi with nearly 

 equal-sized sucker-cups, the suckers being much 

 smaller and the cups much larger and fewer than 

 in Ac Hues. 



Elytra short oval, dilated behind. Intermediate tarsi of 

 male generally dilated. Posterior tarsi fringed on each 

 side in both sexes. Hydaticus, Leach. 



Notevus. 



A. Elytra with coarse punctures, forming three not very 

 regular rows. 



Head and thorax rust-yellow ; elytra light brown. Pro- 

 sternum not ridged in front. In the male the tiftli joint of 

 antennae very large, the sixth much shorter but nearly as 

 broad, the following ones narrow and short, with sharp 

 angles, the last joint oblong, pointed. L. If 1. Eather 

 common. N. clavicor7iis,'De G. 



H, Elytra with scattered punctures, rather fine in front, 

 deeper behind. 



Head and thorax rust-yellow, former behind, latter in 

 front and behind brownisli, disc of thorax usually with a 

 brown spot ; elytra chestnut-brown. Presternum with a 

 fine, sharp ridge. In tlie male the fifth joint of antennae 

 very large, the following five joints almost as broad and 

 not much shorter, with prominent outer angles, last joint 

 much narrower and pointed. L. 2 1. Common. 



N. sparsus, Marsh. 



Laccoj)hilus, 



A, Thorax unicolorous. • 



«. Middle of base of tliorax produced into a very short 

 blunt point ; elytra scarcely transparent. 



Head and thorax yellow ; elytra brown, the outer 



