The insect in question is a member of the group Pedinites family Tenebrionidae as defined by Jacquelin Duval in his “Genres des coleoptères d’Europe”.²

In this group the ♂s often differ very much from the ♀s as in Pedinus or hardly at all as in Phylax— stridulation has not been noticed in any member of this group hitherto. I find it in Pandarus & Heliopathes (including olocrates). In Litoborus an intermediate genus where the tarsi are hardly dilated in the ♂—I do not find it. In Pedinus where the tarsi are dilated, I do not find it however—³ a number of closely allied genera I have not been able to examine.

The insects sent are⁴

Heliopathes gibbus Fabr. Anglia common on the coast

Hel. cribratostriatus⁵ Chev Reynosa in Spain

on the Mountains— They seem to squeak very little in nature— at least I have only once noticed it alive & I have taken some thousands—but when dead it is often apparent in the process of pinning⁶