a Family of the Hymenoptera Heterogyna. 323 



Sp. 10. Dor. atriceps, Shuck. Length 95 lines. 



Expansion 15^ lines. 



Sordide helvolus glaber capite {autennis mandibuUsque badiis exceptis,) afro, 

 facie valde prominente in medio substdcatd, pedunculo abdominis quadrato 

 gibboso. 



Fuscous, opake, glabrous, excepting beneath the thorax, coxae, peduncle, 

 and apex of the abdomen, all of which have moderately long hair : 

 head deep black, except the mandibles, which are dark chestnut; the 

 face very prominent, subsulcated beneath the anterior ocellus; the ocelli 

 placed in a triangle, the anterior at the distance of the diameter of one 

 from the posterior pair : eyes subglobose, very prominent ; scape of 

 the antennae very short, (the remainder deficient) ; mandibles very 

 broad, with a large obtuse triangular projection at the base within, 

 leaving no space between them when closed, their inner edge acute. 



Thorax darker than the abdomen, gibbous in front and at the scutellum, 

 which is transverse and rounded at the apex ; metathorax considerably 

 produced and fringed : wings fuscous, their nervures black, the cubital 

 thick and undulated, the recurrent inserted just beyond the middle 

 of the first submarginal cell, straight; legs castaneous, their knees 

 pitchy, the femora rather broadest at the base, their outline nearly 

 parallel. 



Abdomen elongate, C3'lindrical, obscure, peduncle subquadrate, gibbous, 

 ventral portion very slightly angularly produced, less than the follow- 

 ing segment, all of which are transverse, the terminal segment smooth 

 and shining and very pilose. 



This species is from the Gambia. Although very like the three 

 preceding, it is very distinct in the form of its head, mandibles, and 

 femora. It is the smallest of the genus, and singularly enough leads 

 oft" to the next by the left superior wing, which has an abbreviated 

 portion of a pseudo second recurrent nervure ; by an unlucky acci- 

 dent I destroyed its antennae, and therefore cannot give their pro- 

 portions. 



Genus 4. Rhogmus, Shuck. 



Body elongate, much curved downwards at the apex, cylindrical and cla- 

 vate. 



Head short, transverse ; face slightly protuberant. 



AntenncB short, setaceous, curved, inserted within the inner basal angles 

 of the mandibles upon the margin of the nearly obsolete clypeus, the 

 scape about one-fourth the length of the whole organ, the apex of 

 which will not extend to the insertion of the wings. 



Eyes large, lateral, globose, and very prominent. 



Ocelli large, placed in a triangle on the vertex. 



Mandibles triangular, edentate, slightly curved at the apex, very much com- 

 pressed, convex externally and concave within. 



