672 On Aquatic Carnivorous Coleoptera or Dytiscidcs. 



Dytiscus vittatus. I have seen but few specimens, and it is quite possible that 

 ultimately the two supposed species may prove not to be distinct. 



Madagascar, and Portuguese Guinea. 1045. 



1051. Hydaticus petitii, Aube, M.C — Oblongo-ovalis, sat latus, niger, capita 

 anterius prothoraeeque ad latera testaceis, elytris vitta elongata laterali testacea ; 

 antennis pedibusque anterioribus testaceis, tibiis intermediis piceis, pedibus pos- 

 terioribus piceo-nigris. Long. 16, lat. 9 m.m. 



I see nothing to distinguish this species from H. exclamationis except the larger 

 size, and more oblong form. It appears, moreover, to be variable, the yellow band 

 of the elytra being sometimes very broad and conspicuous, and in other cases much 

 reduced ; the colour of the undersurface and the legs also varies in depth. The 

 largest individual I have seen is from Madagascar, while the smallest — the one in 

 which at the same time the yellow band is most reduced — is from South Africa. 



Madagascar, Abyssinia, South Africa. 1046. 



II. 14. — Group Therjionectini. 



Episternal suture distinctly curvilinear ; spurs of hind tibiae minutely emargin- 

 ate at the apex. 



The six genera constituting this group luay be readily identified by the following 

 abbreviated characters : — 



Elytra closely punctate (in the other members of this group the elytra are im- "I A CI LITIS. 



punctate, except occasionally there is a sexual sculpture in the female. \ ( Yiih below.) 



Cosal lines distinct ; supra-articular border broad ; middle femora Tnth \ TIIERMOXECTES. 

 elongate setse. | {Vide ^. G77.) 



Coxal lines distinct; supra-articular border broad; middle femora wth ) (ETHIONECTES. 



short setae ; prosternum strongly elevate-compressed along the middle. j ( Vide p. 684.) 



Coxal lines obliterated so that no supra-articular border is present ; middle ) SANDRACOTTUS. 



femora -with moderately long setfe. j {Vide ^. 685.) 



Coxal lines obliterated so that no supra-articular border is present ; middle \ EHANTATICUS. 



femora with qiiite short spines. | {Vide ^p. 691.) 



Coxal lines fine but yet distinct ; supra-articular border moderately broad ; ) GRAPHODERES. 



middle femora -vvith rather short stout setas. ' / (Fit/e p. 692.) 



I. Q9.—Gems ACILIUS. 



Elytra punctate ; coxal border distinct, but not very broad. 



The six species of this genus are peculiar to Europe and North America. 



