Odacantha is distinguished from Drypta, to which it is nearest 
allied, by the subfusiform terminal joint of the palpi, the qua- 
drate labrum, the triangular lobe of the mentum, the simple 
labium, the shortness of the basal joint of the antennae, and 
the entire penultimate joint of the tarsi. In describing Po- 
listichus, 1 observed that it was nearly related to Cymindis 
(Tarus Claim, \ and am at a loss to account for the introduc- 
tion of it between Odacantha and Drypta ; such an arrange- 
ment must be entirely artificial, and cannot be justified, since 
it leads to error instead of a correct acquaintance with nature. 
The genus before us contains but one British species. 
O. melanura Linn, 
This elegantly formed and lively coloured insect is an in- 
habitant of reedy fens. It may be found by shaking the reeds 
that have been cut down and tied in bundles for thatching : 
those nearest the water’s edge, or even floating, being the 
dampest, are their most favourite situations; and there in dull 
weather they conceal themselves : they are also found amongst 
the fragments of reeds left after an overflow of marshes; but 
when the sun shines they take wing and are very active. 
O. melanura was first discovered, I believe, at Cromllyn 
Bog, South Wales, by Joseph Woods, Esq., and Mr. Sow- 
erby ; and about the same time John Dere, Esq., and Pro- 
fessor Hooker met with it on the banks of the Yare in Norfolk. 
It has since been taken at Horning, Reedham, and Fakenham, 
in the same county ; also at Whittlesea Mere ; and last May 
Mr. Hewitson directed me to a spot on the borders of a small 
lake at Benacre, Suffolk, the property of Sir Thomas Gooch, 
Bart., where they were tolerably abundant : it is found also 
in June. 
The plant is Potentilla anserina (Silver Weed or Moors 
Corn). 
