Mr. A. G. Butler on the Cocytus Oroup of Adolias. 97 



however, saw no objection to keeping two forms so very dis- 

 tinct (Fieber refers them to different families) as Hydrometra 

 stagnorum and his old G err ides in the same genus and thus 

 entirely ignoring Latreille's more critical acumen, although 

 he was perfectly aware of the fact, as he adds, under Hydro- 

 metra stagnorum, " Hydrometra Latr. Ins." Dr. Fieber quotes 

 Hydrometra, " Fab. S. R. Gen. 37," Gerris being added as a 

 synonym, which it certainly is not if the " S. R." is to be also 

 quoted for it. In the midst of all this most unnecessary con- 

 fusion. Dr. Burmeister slips in with a new name {Limnohates) 

 for this Civiex= Gerris = Hydrometra stagnorum. If anything 

 like a law of priority is to be retained, Hydrometra must be 

 confined to H. stagnorum, Gerris reverting to its original 

 members ; and this may be said for other names besides those 

 mentioned in these remarks, but which, as they do not apply 

 to British species, need not be examined here. 



XVI. — Notes on the Sexes of the Cocytus Group of the Genus 

 Adolias. By A. G. Butler, F.Z.S. 



Since writing my remarks upon Cocytus and its allies, I have 

 made a rather important discovery as regards the sexes of 

 some of the species of Adolias. 



Dr. Felder (Wien. ent. Monatschr. v., December 1860) has 

 described the male of Moore's A. Puseda; at the end of the 

 description he adds the following observation : — " Auctor hujus 

 speciei foeminam tantum cognovit et propter signaturas in sec- 

 tionem A. palungai, pulasaroi &c. palpis distinctissimam lo- 

 cavit. ^4. Cocytus Fabr. proxima autem ejus affinis est." 

 Moore should, however, have placed the Cocytus and Amba- 

 lika groups together, the former being the males of the latter. 



I had previously separated the sexes, both male and female, 

 as being possibly distinct species ; and now that I have been 

 enabled to match them, I find that in almost every case we 

 received the opposite sexes together, and from the same collec- 

 tions ; a comparison of the miderside markings shows similar 

 modiiications of pattern in both sexes. The following altera- 

 tions will therefore have to be made in this genus : — 



1. ^. Adolias Cocytus, Fabricius. 

 $ . Adolias Gojpia'^ var., Moore. 

 Siam (Fabr.) ; Assam. S ? j B.M. 



in its, for the second time, contracted sense. Except for this what is now 

 with all entomologists a synonym, Gerris would disappear with these au- 

 thors altogether from the European list. 



