130 1-^"°^' 



Preservation in formalin vapour appears to be equally useful, and 

 is in many ways more convenient than the liquid medium. A small 

 plug of wool, damped with 40 per cent, formalin, is placed at the 

 bottom of a glass tube, and the insects, together with pieces of the 

 leaf or bark to which they are attached, are dropped into the tube 

 without further treatment. The cork must be a well-fitting one and 

 should preferably be first boiled in paraffine. This method of prepara- 

 tion has the further advantage of preventing deterioration by mould 

 or mites. 



Peradeiiiya, Ceylon : 

 April 10th, 1906. 



HELP-NOTES TOWARDS THE DETERMINATION OF BRITISH 

 TENTHREDINID/E, &c. (U). 



EY THE EEV. F. D MORICE, M.A., F.E.S. 

 NEMATIDES {continued) = PTERONUS, AMAURONEMATUS. 



Pteronus, Jur. 



The s[)ecies placed by Konow in this genus include some of our 

 commonest saw-flies, such as ribesii and myosotidis. All have an 

 incised clypeus and bifid claws ; the puncturation is generally slight, 

 so that the surface is shining, the $ saw-sheath simple and rather 

 small in all its proportions, the antennae long, slender, and tapering. 

 Their bodies, I believe, are never entirely black, though many (especially 

 thcc;^ J) have a good deal of black above, its exact extent being 

 somewhat variable. Often the ground colour is green in life, but 

 fades afterwards to a brownish- or reddish-yellow. In other cases the 

 abdomen is entirely or partly orange, retaining this colour unaltered 

 after death. Some species are difficult to separate for certain in 

 particular specimens, though in other cases they may be known at 

 once by diff"erences in the sculpture of the head, for these characters 

 are liable to be obliterated when, as often happens, the insect shrivels 

 more or less after death. Dirty specimens also, and such as have lost 

 their antennsD, or have been so pinned as to destroy the scutellum- 

 characters, are often impossible to name with certainty, and are really 

 not worth keeping. This applies especially to the green species, 

 most of which are pretty common, and resemble one another so 

 much that the obliteration of a single character may often make them 

 undistinguishable. 



I can certify about twenty species as British, and have added in 



