Mr. A. G. Butler on the Cocytus Group 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 Gerrides 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. g. R. Gen. 37,” Gerris being added as a 
synonym, which it certainly is not if the “8. R.” is to be also 
uoted for it. In the midst of all this most unnecessary con- 
fasion, Dr. Burmeister slips in with a new name (Limnobates) 
for this Cimex = 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. BuTuer, 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. palunge, pulasare &c. palpis distinctissimam lo- 
cavit. A. Cocytus Fabr. proxima autem ejus aftinis 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 underside markings shows similar 
modifications of pattern in both sexes. The following altera- 
tions will therefore have to be made in this genus :— 
1. 3. Adolias Cocytus, Fabricius. 
9. Adolias Gopia? var., Moore. 
Siam (Fabr.); Assam. ¢ 9, 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. 
