122 IIYDRADEPIIAGA — DYTISCIDAE. 



behind middle and a roundisli spot at apex brownish- 

 yellow. 



Oval, rather convex. Head (except vertex) reddish ; 

 thorax blackish, sides indistinctly reddish ; legs brownish- 

 red. Upper-side smooth. Male with swinnning hairs 

 beneath first three joints of posterior tarsi. L. 8^ 1. 

 Common. A. unditlatus, Schr. 



c. Under-side entirely brownish-yellow. 



Oval, tolerably convex. Head yellow in front, bronze- 

 brown behind ; thorax Ijronze-brown, with a yellow trans- 

 verse band (dilated at sides) in middle ; elytra brunze-browu, 

 with side margin, a basal band, dilated within, two longi- 

 tudinal lines (inner one very short), and an oblique band 

 from shoulder yellow. Presternum ridged in front, strongly 

 dilated behind coxae, fiat, hinder process sharp. Male with 

 swinmung hairs beneath first three joints of posterior tarsi. 

 L. of 1. Common. A. maculatus, Liu. 



Di/tiscus. 



A, Posterior coxae with a pointed process l)ehind. 

 a, Scutellum black. 



I, Process of posterior coxae short and ratlier blunt. 



Upper-side dark olive-green ; all the margins of thorax 

 and side margins of elytra yellow ; under-side brownish- 

 yellow. Elytra of female furrowed or smootli. L. 14 1. 

 Common. D. marginalis, Lin, 



II, Process of posterior coxae sharp. 

 Upper-side dark olive-green, all the margins of thorax 



and side margins of elytra pale yellow ; under-side pale 

 yellow. Elytra of female furrowed. L. 14 1. Not 

 common. D. circuincinctua, Ahr. 



h, Scutellum yellow. 



I. Elytra olive-green, with side margin yellow. 



Head and thorax olive-green, all the margins of latter 

 yellow; under-side yellow, with black spots. Process of 

 posterior coxae sharp. Elytra of female furrowed until 

 beyond middle. L. 13 1. Not uncommon. 



D. circ'iiiiiflexiLs, Fab. 



