included in the genus Tropisternus. 95 



identified with any species I know. At the end of this 

 paper I have added some short observations on these 

 doubtful names. 



Section A. 



Posterior tibiae entirely destitute of cilia (or swimming- 

 hairs). This section comprises six groups. 



Group 1. Species having the fissure on the middle of the 

 prosternum open in front as well as below. (Species 

 1 to 6). In all the other groups the divided prosternum 

 is closed in front. 



The insects combined in this group appear to be 

 extremely closely allied, the distinctions being chiefly in 

 the details of coloration. They all have the upper 

 surface yellow, with metallic green parts on the head, 

 thorax, and elytra : these green marks are placed on the 

 posterior part of the head ; on the middle of the thorax ; 

 and on the wing-cases, where they are longitudinal stripes 

 or vittse ; in certain species some or all of these metallic 

 marks become of increased extent so as nearly to cover the 

 whole area of the part on which they are situated, but 

 the margins always remain pale. In other respects the 

 species agree very closely. The epipleural margin is 

 punctate, but the upper edge, on which the punctures 

 are placed, is very narrow, so that the punctures readily 

 escape observation, although they are in fact large and 

 placed very close to one another ; they bear no visible 

 spines, but when the tip of the finger or the edge of a 

 hard instrument is passed over them they are found to 

 be extremely asperate ; they are confined to the posterior 

 half or two-thirds of the margin, no trace of them being 

 visible on the basal portion. The upper inner face of 

 the hind tibia is highly polished, but when examined 

 with a good magnifying-power is seen to be obsoletely 

 sculptured, the shallow punctures being filled up by an 

 extremely fine squamosity. The outer face of the tibia 

 is asperate, with coarse punctures and erect spines, and 

 the line of demarcation between the armed outer face 

 and the smooth inner one is straight, being formed by 

 a series of coarse punctures ; the posterior punctures of 

 this series are not closer to one another than are the 

 basal punctures ; they do not diverge (or encroach) on 

 the smooth inner face and are not armed with fine erect 

 setae. The sternal spine is very acuminate, not fiat, 



