30 BRITISH ICHNEUMONS. [| Exochus 

EXOCHUS. Gravenhorst. 
Gr. I. E. ii (1829). 328. 
Head not declived abruptly immediately behind the eyes, more often 
with vertical dots white; face strongly protuberant and punctate; frons 
centrally triangularly elevated; eyes subemarginate next the scrobes. 
Antennae shorter than body, not incrassate apically with the scape not 
cylindrical. ‘Thorax nitidulous and subdeplanate ; notauli wanting or 
very short; discal metanotal areae distinct with areola strong, though 
usually basally and sometimes apically incomplete ; costulae wanting or 
entire; spiracles oval or subcircular. Scutellum deplanate and not small. 
Abdomen black and _ nitidulous, not scabriculously punctate and at most 
centrally or laterally pale ; basal segment not rugose, distinctly bicarinate 
discally with spiracles at or near the subconstricted base; second not 
carinate nor dull; terebra concealed. Legs short; femora strongly in- 
crassate; hind tibiae bicalcarate, the intermediate of equal or unequal 
length ; claws stout. Wings more usually with the areolet wanting, but 
sometimes entire and irregularly triangular; basal nervure strongly curved 
above, rarely continuous through the median. 
I am quite unable to find any good generic characters in Forster’s 
names 7Z7iclrstus, which has been frequently employed by systematists, and 
Amesolytus, for which Szépligeti has recently discovered new Hungarian 
species. Holmgren in 1873 first made use of Forster's generic names, 
though not his characters; he called Polyclistus, Metacoelus and 
differentiated 77riclistus, not by its lack of costulae, but by its possession 
of alar areolet and interantennal cristulae; his characters were good, and 
I should have been inclined to give them place above Forster’s, had he 
not employed the latter’s names. Thomson in 1887 corrected JZe/acoelus, 
Holmer. to Polyclistus, Forst., and described a genus 77iclzs/us including 
species of Ewochus, Triclistus, and Amesolytus, Forst. ‘These useless 
genera may be thus tabulated :— 
(2). 1. Abdomen petiolate; petiolar spiracles 
beyond centre ft = 2 wALCOLET ES. 
(1). 2. Abdomen sessile; spiracles distinctly 
before centre. 
(8). 3. Basal lateral areae discreted from 
dentiparal (costulae entire). 
(5). 4. Vertex strongly carinate  apsntia: 
with areolet ' . Metacoelus. 
(4). 5. Vertex not carinate posteriorly, 
(7). 6. Head declived immediately behind 
eyes; face longer Polyclistus. 
(6). 7. Head broader behind eyes; face less 
protuberant Exochus. 
(3). 8. Basal lateral areae confluent with 
dentiparal (costulae wanting). 
(10). 9g. Areolet present; metanotal carinae 
incomplete .. Triclistus. 
(9). 10. Areolet wanting; metanotal carinae 
complete ., a he .. Amesolytus. 
