3i8 HYMENOPTERA ACULEATA. 



crest, the actual apical margin is on the ventral side of the 

 abdomen ; seventh dorsal segment inferior, the eighth 

 dorsal hidden in the seventh ; four ventral segments only 

 visible, fifth with a more or less rugose patch in the 

 centre near the apex, sixth very short, clothed along the 

 middle with spine-like, often recurved, or apically dilated 

 hairs, apex of the segment often produced into a mem- 

 branous wing, seventh so fragile and membranous that 

 I have been unable to extract it entire, eighth narrow and 

 tongue-like, armature very large at the base, the stipitea 

 more or less divergent, sagittae convergent and pointed, 

 except in argentata, where both stipites and sagittae are 

 subparallel ; $ with a dense ventral pollen brush, formed 

 of straight, spirally grooved hairs; anterior coxae in the 

 cJ each with a long, thick, blunt spine, and the anterior 

 tarsi sometimes widely dilated. There are seven British 

 species of this cosmopolitan genus; they burrow in old 

 posts, stumps of trees, or banks, the same species some- 

 times being found in banks, sometimes in dead wood ; they 

 all line their burrows with pieces of leaves or flowers, 

 which they cut out in a more or less oval form from 

 various plants, the cells are closed at the top by two or 

 three circular pieces of leaf, placed one over the other, 

 these pieces of leaf are cut out by the ? by means of her 

 mandibles, the bee holding on to the edge of the leaf by 

 her legs until the piece is completely severed, the bees 

 may often be seen flying away with their green burden, 

 looking like flying leaves. 



The specific characters of the members of this genus lie 

 chiefly in the antei'ior tarsi, the ventral segments and 

 armature of the <$ , in the mandiblos, the colour of the 

 scopa, &c., in the ? . The British species may be thus 

 tabulated : — 



(6) 1. cJ , front tarsi dilated, white ; ?, man- 

 dibles flat, deeply furrowed, the 

 furrow extending from between the 



