246 Dr. G. A. K. Marshall on a 



behind the middle of the scrobes ; mandibles each bearing 

 three seta? ; mentum with two lung and four shorter seta?. 

 Prothorax strongly narrowed from base to apex, the sides 

 almost straight or but slightly rounded, not constricted at 

 the base or apex, the base very deeply bisiuuate ; the post- 

 ocular lobes very feeble or obsolete, with a fringe of short 

 vibrissa? ; the front coxae only slightly nearer to the front 

 margin of the prosternum than to the hind. Elytra with 

 v< ry oblique shoulders ; insects winged. Corbels of hind 

 tibiae entirely open and without any internal carina. 



In addition to the genotype, P. fece, Fst., three other 

 previously described species must be included in this genus, 

 namely, Corigetus armiger, Fst., C. turkestanicus, Fst., and 

 Platy tracheitis marmoratus, Fst. (Corigetus hirghisicus, Fst.), 

 all from Central Asia. 



Corigetus (sens, str.) was founded on a Siberian species, 

 ft marmoratus, Desbr., and will probably prove to be a 

 purely Palsearctic genus. From Platymycterus it differs 

 principally in the structure of the rostrum. The scrobes 

 are not so entirely dorsal in position, being linear (more than 

 twice as long as broad), extending for fully half the length 

 of the rostrum and becoming gradually shallower behind, 

 without anv abrupt transverse delimitation; the upper edge 

 of the scrobe is carinate and curves round to the middle of 

 its base, thence running back towards the middle of the 

 front margin of the eye ; the scrobes are widely separated, 

 the space between them being four-fifths the width of the 

 forehead; the hind margin of the epistome is sharply cari- 

 nate ; the mentum bears only four seta? ; the upper surface 

 of the rostrum is strongly raised behind and stands high 

 above the depressed and flattened forehead ; the prothorax 

 is not subconical, the sides being rounded and constricted 

 near the base and apex. 



' In Cyrtepistomus, Mshl. (Ann. & Mag. Nat. Hist. (8) xii. 

 3913, p. 186), and Cyphicerus, Schh., the scrobes are ill- 

 defined posteriorly ; the prothorax is not or only slightly 

 narrower at the apex than at the base, the basal margin 

 being subtruncate or very shallowly bisiuuate ; in the former 

 genus the mentum bears four seta?, in the latter it bears only 

 two and the corbels of the hind tibia? contain a well-marked 

 carina. 



The following is a hey to the species at present known 

 to me : — 



1 ( 6). Joint 2 of funicle longer than 1. 



2 ( 5). Colour green below and brown or grey 



above, with a green patch round the 



