a Family of the Hymenoptera Heterogyna. 269 



MaxillcB obsolete ? 



Maxillary palpi two-jointed, the joints minute, subglobose, abruptly trun- 

 cated, the terminal one rather the smallest, both having divergent 

 setae at their apex. 



Labial palpi two-jointed and in advance of the maxillary, than which they 

 are rather longer, the basal joint subobconic, the terminal one minute 

 and subulate, and both with divergent setae at their apex. 



Mentum waved laterally and eraarginate in the centre. 



Labium membranous, triangular. 



Thorax subcylindrical, very gibbous at both extremities. 



Prothorax extending laterally to the insertion of the anterior wings. 



Mesothorax largely developed, advanced considerably beyond the insertion 

 of the anterior wings, gibbose in front and suspended over the pro- 

 thorax. 



Scutellum large, usually transverse, gibbous, rounded at the apex. 



Metathorax not largely developed. 



TegidcB small, slender, and linear, but distinct. 



Superior wings not so long as the abdomen, with one marginal and two 

 submarginal cells, the first of the latter much longer than the second, 

 and receiving the single recurrent nervure usually near its middle. 



Legs short : coxcb large, convex beneath and concave above : trochanters 

 triangular : femora quite glabrous and shining, very much compressed, 

 usually triangular and broadest at the base : tibicB smooth, shining, 

 slender, not so long as the femora, and furnished at the apex with a 

 single calcar, at the insertion of which there is usually a coronet of 

 small spines : tarsi longer than the tibiae and very slender j the basal 

 joint as long as the three following, the fourth the shortest, and the 

 fifth terminal joint supplied with a pair of short stout simple claws, 

 and having a moderately large pulvillus between their fork. 



Abdomen elongate, cylindrical, frequently slightly clavate towards the 

 apex, where it curves downwards ; the first segment variously formed 

 and separated from the following by a deep incision, forming a sort of 

 peduncle always convex above : the penultimate and antepenultimate 

 segments equal or subequal : the male sexual organ frequently pro- 

 truding. Type of the genus Mutilla Helvola^ Lin. 



This genus is restricted to the old world, and its metropolis ap- 

 pears to be Africa, from the southern extremity of which one spe- 

 cies, the type, comes in considerable plenty, which renders it strange 

 that nothing should come with it that might with any probability 

 be associated as the female. But if my assumption should be right 

 as regards the female of Labidus, the supposition is that it also has a 

 blind female which never or rarely quits its subterranean abode. 



The generic differences throughout this family are strongly con- 

 firmed by the structure of the male sexual organs, which have also 

 specific diversities, and thus here obtain a value not usually acceded 



