HYMENOPTERA. 283 



the third and fourth segments having patches of silvery pubes- 

 cence. 



Hab. Brazil. (Coll. F. Smith.) 



Genus 36. THALESTRIA, n. g. 



(F. Smith's MSS.) 



The ocelli placed in a triangle on the vertex ; the labial palpi 

 four-jointed, the basal joint about two-thirds of the length of the 

 raentum, the second joint half the length of the basal, both 

 covered with scattered pubescence. The maxillary palpi have 

 one joint, and a small tubercle at its base. The labrum 

 transverse, rounded at its angles, and tuberculate on each side at 

 its base. The superior wings having one marginal and three 

 submarginal cells ; the former about the length of the three 

 latter united, rounded at its apex ; the second and third submar- 

 ginal cells narrowed towards the marginal, the second receiving 

 the first recurrent nerviue a little beyond the middle ; the second 

 recurrent nervure received by the third submarginal cell about 

 one-third from its apex. The calcaria simple. 



1. Thalestria smaragdina. 



Female. Length 8 lines. — Black, the face and cheeks have a 

 dense short pale ochraceous pubescence, the clypeus more or less 

 naked, truncate anteriorly and finely punctured, the pubescence 

 (or scales) which decorate the thorax, briUiant green ; anteriorly 

 and down the centre intermixed with black ; the collar on each 

 side, a ring surrounding the tubercles, a spot beneath the v^dngs, an 

 epaulet over the tegulae, and the metathorax on each side having 

 a tuft of pale yellowish-white pubescence; the scutellum fui-- 

 nished behind with two pointed tubercles, and on each side with 

 an acute incurved spine ; the legs have a green iridescence, the 

 apex of the femora and tibiae having tufts of white pubescence ; 

 the wings hyaline, clouded at their apical margins. Abdomen, 

 conical and covered with a brilliant green eff'ulgence above, 

 changing in certain lights to black or deep green ; the extreme 

 lateral margins of the three apical segments have a narrow stripe 

 of white pubescence ; beneath, the abdomen is naked and of a 

 changeable blue-black colour. 



Male. — Rather smaller than the female, and similar in colour, 

 the thorax having a black pubescence, intermingled with obscure 

 green on the disk, the scutellum similarly adorned ; the abdomen 

 is brilliant as in the other sex, the secgnd and three following 



