2 HTMENOPTEEA. 



In this and the following families I have had figured by Mr. William Chaffers the 

 male genital organs wherever these exhibit any specific distinctions; for it must be 

 recollected that they do not vary to the same extent in all families. When they do 

 differ their form affords most valuable aid in discriminating the species ; and in my 

 opinion they should be figured whenever possible. In the various families the male 

 organs vary exceedingly, to such an extent that in some of them it is not easy at first 

 to trace the homologous parts. 



For taxonomical purposes we may distinguish three distinct parts : — 



1. The basal piece, or cardo. This does not show much variety in form, though not 

 always of the same length or breadth. 



2. The forceps, or stipes. This is the outer piece, and shows very great variation in 

 form and clothing. It divides itself into three, or in some cases four, parts : — 



a. The branch, which is the outermost portion, and, as often as not, bears hairs or 



bristles. It is sometimes one-, sometimes two-jointed, the second joint being 

 formed by the separation of the top from the basal part ; and usually takes the 

 form of a palpiform articulation, to which the name of lacinia has been given. 



b. The volsella, which is in most families a very characteristic piece. It is some- 



times broad, flat and lobe-like, sometimes cylindrical. 



c. The tentaculum, or pincers of Dufour. This is not invariably present. When it 



is, it assumes different forms — round, broad, or palpiform ; and the apex some- 

 times ends in a spoon-shaped process, surrounded with hairs, and sometimes 

 terminates in a beak or hook. 



3. The sagittse, or hamuli; the " baquettes cornees" of Dufour. These are the 

 central pair of organs, and have the penis placed between them ; but the latter can 

 seldom be observed. The sagitta, like the other parts, has a particular form in the 

 various families, and terminates in teeth or hook-like processes. At its base is a kind 

 of envelope — the spatha or " fourneau de la verge " of Dufour. 



In the Sphegidse the male armature is rather characteristic. The branch of the 

 forceps is stout, flattish, broad or narrow at the base, and becomes narrowed at the top, 

 where it, as a rule, curls over the sagittse. It is but seldom two-jointed, and frequently 

 is pilose at the top, and sometimes at the middle. The volsella is characteristic; it is 

 flat and broad, and towards the apical two thirds on the inner side it becomes narrowed 

 from the inner to the outer side into a more or less fine point. The tentaculum is 

 narrow, but not cylindrical ; it usually reaches near to the top of the volsella, and ends 

 in a variably-shaped organ, which, however, generally takes the form of a beak, hook, 

 or spoon-shaped process. The sagittae project above the volsella; they are narrow, and 

 terminate in a lobe-like process, which frequently bears a hook. 



