188 THE ENTOMOLOGIST. 



A NEW GENUS OF COLEOPTERA OF THE FAMILY 

 PSEPHENIDiE. 



By C. J. Gahan, M.A. 



The interesting and remarkable beetles •which form the 

 subject of the present paper were discovered by Dr. A. D. 

 Imms, who found them in all their stages in rocky, swiftly 

 running streams — the larvae and pupae adhering to stones, and 

 the imagines, newly emerged from their pupa-cases, resting 

 submerged under stones alongside their empty pupa-cases. As 

 Dr. Imms proposes to describe fully and give figures of the 

 larvae and pupae, the imagines alone will be dealt with here ; but 

 in referring them to the family Psephenidae I have taken into 

 account the habits of the insects and the great general re- 

 semblance which the larvae bear to those of Psephenus. 



One or two characters possessed by these beetles suffice to 

 distinguish them from all other known Psephenidae, and from all 

 but a few genera of Coleoptera. (1) The elytra do not meet in 

 the middle line to form a suture in any part of their length. 

 When first I noticed this character I thought it might possibly 

 be due to immaturity, as most of the specimens under observa- 

 tion had apparently only just emerged from the pupa. But Dr. 

 Imms was able to tell me that two specimens swept from grass 

 and fully mature were like the rest in having the elytra rather 

 widely separated from one another. (2) The middle area of the 

 metanotum, behind the broad scutellum, is not grooved along 

 the middle (as it is in the great majority of beetles), but is 

 convex along the middle and marked with a groove along each 

 side. This character is evidently correlated with the first, and 

 shows pretty conclusively that the elytra never do meet in the 

 middle line. We find the metanotum similarly devoid of a 

 median groove in the heteromerous genus Rhipiphorus, in which 

 the elj'tra are small scale-like structures, which do not meet 



