4 MEMOIRS ON THE COLEOPTERA. 



well known character to a position of primary importance in group- 

 ing the genera and subgenera; this relates to the degree of inflexion 

 of the hypomera or inflexed sides of the pronotum, which divides 

 the group into three very well defined sections thus: 



I Hypomera moderately inflexed, nearly flat and wholly or in great part 

 visible from the sides, including such genera as Metaxya, Hydrosmecta, 

 Atheta and many others. 



2 Hypomera horizontal, though because of considerable warping of the sur- 

 face, visible in very limited part from the sides, including Dimetrota, 

 Datomicra and others. 



3 Hypomera strongly inflexed, in such manner as to be wholly invisible 

 when viewed from the sides and including Acrotona, Colpodota, Copro- 

 thassa and others, as well as some related but distinct groups, such as 

 the Hoplandriae. 



The body in the first of these sections is more or less parallel 

 and of larger size as a rule, in the second rather small to minute 

 and generally with more tapering abdomen; in the third the body 

 becomes on the whole still more limuliform, or with strongly tapering 

 abdomen. The second character in point of importance relates to 

 the formation of the sterna between the middle coxae, and then 

 follow several characters more particularly important in certain 

 subsidiary sections, such as tarsal structure, impression of the ab- 

 dominal tergites and form of the head, antennae and lateral carinae. 

 Under the second of the above groups we have genera with the head 

 parallel and others with the head basally inflated, and, among the 

 latter, some with finely and others with coarsely faceted eyes. So 

 it becomes sufficiently evident that we have among the Athetae an 

 unusual diversification of structural features. 



The group Athetae, as here construed, comprises the single genus 

 Atheta of Fauvel, Bernhauer and some other recent authors. 



Atheta Thorns. 

 Stethusa n. subgen. 



If Dr. Bernhauer had examined the under surface of his Atheta 

 klimschi, which he assigns to typical Atheta, he would probably have 

 observed that in sternal structure it bears very little resemblance 

 to the true Atheta, where the mesosternal projection between the 

 coxse is more or less prolonged and slender to aciculate. In this 

 subgeneric group the sterna between the coxae are notably 



