30 Rev. T. A. Marshall's Monograjjh of 



yellow. Antenntc ll-juinted, tliickened towards the tips, shorter 

 than the body, black with the 3 basal joints testaceous. Metathorax 

 carinated in the middle, regularly areated. Wings hyaline ; 

 squamuhc fuscous ; radicles testaceous ; nervures very slender, those 

 -of the basal region brownish, the radial and border of the stigma 

 testaceous, the latter very pale, hyaline. Legs flavotestaceous ; the 4 

 posterior brown with the knees and base of the tarsi pale ; hind cox;o 

 brown. Abdomen longer than the head and thorax, lanceolate, 

 compressed and pointed at the apex ; 1st segment linear, 2^ times as 

 long as broad, having its tubercles placed before the middle; 2nd> 

 reddish brown in the middle, blackish on the sides ; following 

 segments black. Valves of the terebra black, compressed, curved 

 downwards in form of a stout claw ; appendages of the ventral valve 

 testaceous. ^ Unknown. Length, | ; exp. Ih lines. 



A single $ was bred by Bignell from Callipterus 

 letidarius, the puceron of the birch, Betula alba. 



6. Trioxys ccntaurex, Haliday. 



Aphidius (T.) ccntaurccV, Hal., lib. cii., 490, $ . 

 T. ccntaureie, Marsh., lib. cit., p. 554, ^ ^ . 



9 Appendages of the ventral valve black. Black, shining. 

 Antennae 11-jointed, filiform, longer than the head and thorax, but 

 shorter than in auctus, black with the 2nd joint and base of the 

 3rd testaceous. Palpi brownish. Thorax glabrous ; mesothoracic 

 furrows distinct. Wings hyaline ; squamulte and radicles dull 

 testaceous ; stigma very pale yellow after death ; nervures slender, 

 brownish. Legs dull testaceous ; coxa), femora, and tibiai of the 4 

 posterior in great part inf uscated ; trochanters and base of the tibiae 

 testaceous. Abdomen linear-lanceolate, black ; 1st segment narrow, 

 testaceous at both ends, or entirely ; 2nd narrowly testaceous at the 

 extremity ; tubercles situated beyond the middle (a character 

 peculiar to this species and the following). 5 Similar ; antennae 

 rather shorter than the body, 13-jointed, with the extremity of the 

 2nd joint and base of the 3rd testaceous ; legs darker than those of 

 the $ ; abdomen rounded at the apex. Length, 1 ; exp. 2 lines. 



Not common, according to Haliday. The $ when 

 engaged in oviposition behaves like an ApMdius : she 

 applies the terebra to the belly of the puceron ; the stroke 

 cviven is instantaneous ; the two remarkable processes or 

 horns of the 6th segment are quite useless in the opera- 

 tion. Haliday once reared this parasite from the aphis of 



