324 



British Dragouflics. 



colours almost without change. The reagent formalin, 

 which is now taking the place of spirit to a great 

 extent as a preservative, since it has the great merit 

 of not rendering brittle the insects placed in it, does 

 not seem so safe in the matter of colour preservation. 



Mr. S. L. Mosley, in the E. M. M., 1876, p. 89, 

 suggested filling the bodies with plaster of Paris till 

 they were dry. But, apart from the weight of the 

 substance and the chance of its setting inside the 

 abdomen, the method does not appear very practicable, 

 seeing that it is necessary to set the insects as soon as 

 they have been eviscerated. 



It is usually the custom, with those Dragonflies that 



1^ r-4#:i^ 



1 r 



/H ^ 1 



Fig. 55.— Setting-Board for Dragonflie.s. 



(!., Cork, b.. Deal. 



are not eviscerated, to pass a grass-stem or bristle from 

 the thorax into the abdomen to keep them from 

 breaking at the segmental sutures when the\- are dry. 

 The insects to be so treated will be the genera 

 LcHcorrJii}iia and Syiupcinmi, the sub-families Cordiiliimc, 

 and perhaps Gomphimc, and the famih- Agrioiiidcc. 

 For the last a shoemaker's bristle is \ery suitable, 

 or for the very smallest even a horsehair. In no 

 case must the grass-stem or bristle disarrange 

 the ninth or tenth segment, or the second of the 

 male. 



