1. PACHYGASTER 73 



Synonymy. — Not mucJi doubt can attach to Zetterstedt's original description of 

 P. tarsalis, and Loew has pointed out that /-*. rohiistics of Jaennicke is obviously 

 only the same species. Considerable doubt must however arise concerning 

 P. meromelas Dufour, especially as two males in Bigot's collection (on one pin and 

 with a pupa case (tig. 100) attached), which were evidently so named by Leon 

 Dufour himself, are only P. tarsalis, and two others (upon another pin) are a female 

 P. tarsalis (with orange antennai) and a probable male P. orbitalis. It is notable 

 also that the only specimen of P. tarsalis which had previously been bred (as 

 mentioned above) came from a rotten pojilar. I have dealt with this at greater 

 length under the synonymy of P. orbitalis, because that has usually been considered 

 a synonym of P. meromelas. An additional ground for confusion has evidently 

 arisen in that both Jaennicke and Loew professed to know the male of P. orbitalis 

 or meromelas in specimens which had the eyes touching, a circumstance which tends 

 to prove that they both must have had males of P. tarsalis before them when they 

 described the supposed male of P. orbitalis. It appears, therefore, that neither 

 Jaennicke, Loew, or Leon Dufour knew what they meant in both sexes under the 

 names of P. argentifer and P. meromelas. I find that I have a note about three 

 specimens of /■'. meromelas in Dufour's collection, now in the Jardin des Plantes at 

 Paris ; they consist of two males of P. tarsalis accompanied by a very long-haired 

 pupa, and a broken third specimen which is certainly not P. orbitalis. 



4. P. orlbitalis Wahlberg. Wings all hyaline ; femora black except at 

 the tip. Eyes separated, and the sides of the face silvery white, in both 

 sexes. 



A shining black species with hyaline wings and black 

 femora. 



(J. Head (fig. 96) about one and a half times higher than long when seen in 



Fig. 06. — rachygnslcr orbilalls S- < 33. Fia.97.—raclujgastcrorhil(ilis ,} . x 33. 



profile. Frons practically bare, at its narrowest part (fig. 97) about one-sixth or 

 one-seventh the width of the head, but slightly widening up to the vertex and 

 down to the antenna?, shining black with the shining black ocellar triangle 

 considerably elevated and surrounded by a polished triangle which is con- 

 tinued rather widely down the middle to the white patches above the 

 antennae, while the sides of the frons are slightly duller and are very sparselj'- 

 punctate ; above the antennae there is a pair of large almost silvery white 

 l)atches which occupy the whole width from eye to eye, but which have a narrow 

 channel dividing them. Face steadily widening downwards from the antennie 

 to the lower angle of the eyes, where it is nearly one-third the width of the 

 head ; the whitish patches above the antennae are continued down the si les 

 of the face as conspicuous almost silvery M'hite eyemargins, which leave only 

 about tlie middle third of the face black ; pubescence absent except for the white 

 down on the eyemargins ; jowls very narrow, black, and merging into the veiy 

 slightly inflatecl lower part of the back of the head ; higher up on the back of 

 the head there is a very narrow shining black rim almost behind the edge of 

 the eye, on whicli is a very short though close black postocular ciliation ; 

 vertex shining black, with minute black pubescence behind the ocellar 

 triangle ; proboscis black, pubescent, mainly retracted into the mouth- 



