June, 1907. J 121 



ON THE ELATERID GENERA HYPNOIDUS, Stepu., 

 AND CRYPTOIIYPNUS, Escn. 



BY C. J. GAHAN, M.A.., F.E.S. 



The species of Elaierida that were iiicl tided in the <:;enus TFi/p- 

 noidiift in the first edition of Eeitter's " Calalogus Coleopterorum 

 Europre " are, in the last edition, rightly ranged under two different 

 genera. These genera are easily distinguishable by an important 

 difference in tlie structure of the acetabula of tlie middle cox®. In 

 one, the mesothoracic e[)imera extend to the acetabula and take part 

 in their external boundary ; in the other genus they are completely 

 shut off from the acetabula, owing to the meeting together of the 

 lateral parts of the mcso- and uieta-sternum. This distinguishing 

 character was first used by C. G. Thomson, then by Schiodte, and its 

 value has since been recognised by Champion, Horn, Reitter and 

 others, liut what I wish more particularly to point out is that, with 

 the single exception of Schiodte, these authors have applied the generic 

 names Hypnoidus and Crt/ptohjpnus in a way almost exactly the 

 reverse of that in which they were used by Stephens, who in this 

 matter holds priority. 



When Stephens founded the genus Jlijpnoidm (111. Brit. Ent., 

 Maud, iii, p. 2G0, 1830) he arranged the species in two sections. In 

 the first section he placed II. riparms, Fab. ; the second section 

 including a(/ricol(t, Zett., quadripustidattis, Fab., dermcstoides, Ilerbst, 

 and pulcheUiis, Linn. II. ripariics, Fab., ought therefore to be 

 regarded as the type of Ili/pnoidus, Steph. x\ny doubt as to tliis 

 should be removed by a consideration of Stephens' subsequent 

 procedure. In his "Manual of British Coleoptera," p. ISO (IS39), 

 he raised his two sections to the rank of genera, characterising the 

 first under the name of Ilypolithiis, Esch., and the second as Crypto- 

 Injpnus, Esch. ; so that here, for the first time, the two genera are 

 separated and the name Gryptoliypnus is given a definite application, 

 being restricted to those species which Stephens ])laced in his second 

 section. It is evident also that he dropped Ilj/pnoidas as a synonym 

 of the earlier described Ilypolithus, Esch., not knowing that the 

 latter name was pre-occupicd and could not be used. Schiodte 

 adopted the same names as Stephens for these two genera ; and, 

 except that Uypnoidus must replace IlypoUthiis, this is the course 

 which, in my opinion, ought to be followed. 



In accordance with (his view, the two genera and the British 

 species may be arranged as follows : — 



