British Braconidm. 75 



Prov. These insects, or at least two of them, diifer 

 materially from those of Europe by their habits, being 

 parasites of Aphides ; fiavocincta is of unknown origin. 

 It is therefore not without reason that the transatlantic 

 entomologists have regarded them as generically distinct 

 from Pachylomma. This genus, to which our attention 

 must now be confined, has been treated as a near relation 

 of ApJiidius, and this idea seems based upon the fact that 

 two of the American insects just mentioned are parasites 

 of pucerons, resembling in that single respect the ex- 

 tensive tribe represented by Aphidius. Notwithstanding 

 similarity of parasitism, which by itself is plainly insuffi- 

 cient to prQve affinity, I venture to think that, in com- 

 paring Pachylomma with Aphidiits, authors have suffered 

 themselves to be misled by a merely illusory resemblance. 

 Admitting that, at first sight, the general form of Pachy- 

 lomma may possibly suggest that of an Aphidian, yet a 

 closer inspection of structural details must lead immedi- 

 ately to the abandonment of the idea. An ordinary lens, 

 applied to a Pachylomma, reveals the following primary 

 characters : oral parts produced into a rostrum ; wings 

 equipped with a complete neuration, not only different 

 from that of Aphidius, but from that of all other Hymen- 

 optera ; the insertion of the abdomen upon the metathorax, 

 faintly suggestive of the structure of Evania ; the articu- 

 lation between the 2nd and 3rd segments, which is 

 effected by imbrication, and not by juxtaposition ; finally, 

 the form of the hind legs, elongate, with lengthened coxae 

 and incrassated tarsi. These peculiarities constitute a 

 distinct facies, of which not the smallest trace is to be 

 found in any genus of the Aphidian group. I fail, there- 

 fore, to perceive any analogy between Pachylomma and 

 Aphidius. Mr. Ashmead is of a different opinion; he 

 expresses himself much struck by the similarity of these 

 two genera,* without however particularising the points 



* See Proc. Ent. Soc. Washington, 1894, vol. iii. no. 1, " Notes on 

 Pachylommatoidse ." According to the description of EujMchylomma 

 rileyi, it appears that that insect scarcely differs from Pachylomma. 

 The writer of this interesting memoir has done well in correcting 

 the original mistake of assigning his Eupachylomma to the tribe 

 Euphoridse and genus IVesmaelia, Forst., which is quite out of the 

 question. I may remark also that, in speaking of the mode of 

 insertion of the abdomen of Pachylomma, Mr. Ashmead quotes, as 

 an example of the same peculiarity, Cxnoccelius, Hal., which is quite 

 correct ; but he is mistaken in supposing that my genus Promachus 



