178 PERCY SLADEN TRUST EXPEDITION 



Morne Seychellois at 1500 — 2000 feet in February, 1909; from forest land on Cascade 

 Estate, near Mount Harrison, at 1700 feet, early in the following month; and from forest 

 above Cascade Estate in January, 1909, where also the typical female occurred in the 

 following month, at an altitude of between one and two thousand feet. 



Plectiscus Gravenhorst, Ichn. Europ., ii (1829), 978; Thomson, O. E. xii, 1296. 



Head with vertex distinctly transverse ; cheeks not buccate ; face parallel-sided, 

 glabrous and not apically constricted ; clypeus convex and laterally compressed, trans- 

 versely discreted; lateral metathoracic areae complete; basal abdominal segment elongately 

 petiolate ; areolet distinct and entire, not transverse. 



These characters will serve to distinguish the present genus from all others of its 

 Tribe ; from Dicolus, the areolet renders it distinct. 



17. Plectiscus oceanicus, sp. n. 



A small, nitidulous, black insect with the prothorax, legs except apically and centre 

 of abdomen, pale ; hind tibias centrally pale banded ; areolet entire. Length, 3 mm. 

 $ only. 



So similar to the last-described species [Dicolus equatorius) as to need no detailed 

 description. Therefrom it differs only in its transverse vertex, deeply puuctiform notauli 

 of the mesonotum which is not centrally impressed, the deplanate and coriaceous and 

 apically subexplanate basal segment, apically compressed abdomen, longer terebra which 

 is hardly shorter than the abdomen, basally stramineous anterior legs, immaculate 

 testaceous hind femora, centrally stramineous hind tibia?, small and quadrate alar areolet, 

 and opposite nervellus. 



Mahd : a single female was captured in the Mare aux Cochons district, at an altitude 

 of between one and two thousand feet, at the end of January, 1909. 



Thersilochus Holmgren, Sv. Ak. Handl., 1858, n. 8, p. 135. 



18. Thersilochus evanescens, sp. n. 



A small black species with the mouth, antennae basally beneath, and centre of 

 abdomen, pale. Head transverse and closely punctate, subbuccate behind the internally 

 parallel eyes ; face somewhat dull and white-pilose, transverse and centrally prominent ; 

 clypeus strongly discreted, strongly transverse, elevated with its apex glabrous and, like 

 the mouth, testaceous ; cheeks not short. Antennae somewhat short, hardly extending 

 beyond metathorax, stout and filiform, apically subclavate, with their pale bases broadly 

 separated and scrobes distinct. Thorax short, punctate and somewhat dull, black with 

 the mesopleurse below radices, and the propleurse, ferrugineous ; notauli wanting ; 

 metathorax short and evenly punctate with a single lateral carina, from near the apex of 

 which the discal transcarina extends obliquely to centre of the small basal area. Scutellum 

 black. Abdomen pyriform, nitidulous, with the second and third segments indefinitely 

 testaceous apically, and the compressed anus rufescent ; basal segment smooth, elongate, 

 obsoletely punctulate with the postpetiole a third length of petiole and parallel-sided ; 



