136 Trans. Acad. Sci. of ^t. Louis. 



yet these two genera are placed at the opposite ends of the 

 series in the catalogue of Ileyden, Reitter and Weise. The 

 species are rather numerous but appear to be very rare in 

 individuals. Mr. Reitter has recently sent me a male of 

 riijicornis Grav. 



PoLYSTOMOTA u. gen. — This genus is founded upon the 

 European Polystoma grisea, of Kraatz, and there may be one 

 or two other species of the palaearctic fauna which will prove 

 to be congeneric. On comparing this species with Emplenota 

 (Polystoma) algarum, of Fauvel, it can be readily seen that 

 the upper surface has none of the exceptionally depressed 

 character that distinguishes the genus Emplenota, and closer 

 observation shows that the iutermesocoxal parts and hind tarsi 

 are very different in organization. In fact Polysfomota forms 

 a bond between the isolated Emplenota and the equally dis- 

 tinct Rheochara, but with characters differing so greatly from 

 either as to necessitate a separate genus. 



Aleoehara Grav. 



The chief special characters of this genus are the simple 

 non-carinate mesosternum, always more or less widely separ- 

 ating the coxae and extending to the posterior limits of the 

 latter, the metasternal process being short and broad or oc- 

 casionally subobsolete, the strongly inllexed hypomera and 

 the feebly modified third ventral plate, the first two being 

 distinctly and acutely impressed. In addition, the punctua- 

 tion of the pronotum is invariably rather fine and even, that 

 of the elytra but little coarser and somewhat closer, while the 

 punctures of the abdomen are more or less obviously coarse 

 and notably sparse throughout the genus. The elytra are 

 feebly sinuato-truncate at apex, without trace of external 

 sinus. The species are somewhat heterogeneous in antennal 

 structure, some having these organs short, thick and fusi- 

 form, while in others thev are much longer, less thick and 

 gradually enlarged to the tip, also in the nature of the male 

 sexual characters, the apex of the sixth dorsal plate being 

 either simple and subtruncate in that sex or pectinate as in 



