1880 .] 
25 
[Packard. 
Gexus Microgaster. 
Head moderately large, transversely elliptic o-cubieal ; ocelli 
usually prominent, front sometimes carinate in $ just below the 
insertion of the antennae, but usually smooth. Eyes of moderate 
size, covered with fine hams. Antennae rather thick, long, fili- 
form. Fore-wings with a large, broadly triangular, conspicuous 
dark pterostigma ; first subcostal cell large, more or less regularly 
polygonal ; a second subcostal cell often present, especially in the 
larger species, very small, the outer side being usually obsolete. 
Legs pretty stout, with the hind femora often considerably 
swollen. Abdomen sessile, short, with the two basal segments 
varying: in relative length and the sides raised into a ridge, 
coarsely punctured, while the rest of the abdomen is highly pol- 
ished. The ovipositor is either short and hidden or exserted, and 
about as long; as the abdomen is wide, the outer blades thickening: 
towards the tip, or just before the tip. 
The species are usually quite small, and live in great numbers 
in caterpillars; before pupating they bore through their host, and 
spin their cocoons on the outside of the caterpillar or on leaves 
and twigs, forming a small mass of silk enveloping the cocoons 
which stand up on end, side by side, fifty or more in number. 
Microgaster carinata n. sp. 
One S, six 2. This species is much larger than the others 
noticed in this paper, and differs in the second subcostal cell 
being present and in the ovipositor being long and exserted. It 
belongs to the same section of .the genus as Linnaeus’ M. globa- 
tus, though considerably smaller and differing in other res]3ects. 
Head moderately large, with long, dense white hairs, the front 
just below the antennae brownish black, palpi hairy, pale yellow. 
Head and body deep black ; metathorax coarsely pitted ; propo- 
dium short, with coarse, confluent punctures, and a decided 
median ridge. Tegulae black. Wings clear, pterostigma moder- 
ately broadly triangular, dark brown, veins dark brown ; second 
subcostal cell minute, elongate, triangular, with the outer sides 
partly open. Legs with the trochanters all black. Fore and 
middle legs honey-yellow (beyond the trochanters), claws dark. 
Hind femora and tibiae yellow, with a slight reddish tinge, and 
