232 JAMES WATERSTON. 



wings and legs. The latter parts should be arranged to show both sides ; the 

 chaetotaxy of the under surface of the wings and the posterior aspect of the legs 

 (especially the apical armature of the tibiae) is often of great importance, and can be 

 studied accurately only by methods such as are outlined above. 



When a species has been founded on a single example, the type is treated in the 

 following way : — the wings on one side having been removed are passed through oil 

 and mounted in balsam ; the legs on one side are taken off, heated in potash, put 

 through glacial acetic and oil, and then mounted ; in the same way one antenna 

 is mounted, the head being variously treated. If the species be one with a thick 

 deeply sculptured integument, it is best, I think, to treat for a short time with hot 

 potash and then to dissect out the mouth-parts in acid and mount them. A fine pin 

 is now inserted into the cavity made by the removal of the trophi, and the head set 

 aside to dry ; after this the smallest possible drop of viscid xylol-balsam is employed 

 to fix the head firmly to the pin ; the balsam must not be thin or it will run over the 

 sculpture of the frons and ruin the preparation. The specimen may now after relaxing 

 be set on card with the head alongside, one antenna is left on to show the relative 

 length of the scape and the scapal groove, etc. Neither the colour, the metallic lustre, 

 nor the ordinary bristles of strongly chitinised heads will alter by this treatment, 

 but it should not be employed w^here the bristles are stout, flattened and scale-like, 

 as they are apt to become detached in the process. In such cases one can only dissect 

 the mouth-parts when the specimen has been properly relaxed ; the mandibles, 

 however, are hard to remove when the muscles have not previously been softened 

 by caustic potash, and the labrum as often as not is lost or torn ; when the head is 

 weakly chitinised and non-metallic, it is perhaps better studied mounted like the legs 

 and wings. Speaking generally, all larger, more heavily-chitinised Chalcids should 

 be carded ; theoretically, no doubt, specimens mounted on a pin point or at the end 

 of a long triangle of card give the greatest facility for study, as they can be looked at 

 from all points of view ; but in practice the advantages are mainly with material set 

 and gummed down in the way described. The carded specimen is much more safely 

 held ; e.g., there are still Walkerian and Westwoodian types in the British Museum 

 collection dating from the forties or earlier in excellent preservation, while many 

 St. Vincent examples (1894) pin- mounted, have been destroyed or become reduced to 

 a thoracic torso through vibration in opening of drawers or rough handling ; and if it 

 is desirable to inspect the thoracic sternum the specimen can be floated of! in a moment 

 on a drop of water, dried, examined and tacked down again. All small Chalcids are, 

 however, much better mounted in Canada balsam, except such insects as small 

 Pteromalids or Entedonines, whose hard metallic integument appears opaque and 

 without detail under such conditions. With fragile Chalcids (some Aphelinines, 

 Eulophids, Trichogrammatids, etc.) one must be more careful. It is quite safe to 

 bring them at once from potash to glacial acetic acid, but thereafter the specimens 

 must pass successively through half absolute and half acid, and pure absolute alcohol, 

 and be finally brought into oil by placing in a tube graduated from pure oil at the 

 bottom to absolute alcohol at the top. 



When one is compelled to make a type of any of the more minute and stoutly 

 built forms [e.g., Coccophagus) it is best, I believe, not to mount the insect entire, 

 but to put — of course on the same slide — the following parts under separate cover 



