124 CRABRO DIMID1ATUS. 



silvery pubescence ; the mandibles ferruginous, with their base 

 black, sometimes yellowish in the middle. Thorax shining and 

 finely punctured ; the metathorax with a smooth shining space 

 at its base, the sides covered with fine silky pubescence, in the 

 centre is a longitudinal impressed line which extends from the 

 base to the apex, at the latter it runs into a deep fossulet ; the 

 tubercles and tegulse testaceous ; the wings hyaline and irides- 

 cent, with the nervures piceous ; the apex of the anterior 

 femora, the tibiae and tarsi yellow; the base of the intermediate 

 and posterior tibiae, and the tarsi of the former, yellow; the 

 apex of the intermediate and posterior tibiae ferruginous ; the 

 tibiae very spinose. Abdomen smooth and shining ; the margin 

 of the petiole and of one or two of the segments rufo-piceous, 

 the apical segment ferruginous. 



The Male differs in having the second joint of the antennae pro- 

 duced into a tooth at its apex, the third very minute, the fourth 

 considerably swollen, and as long as the fifth, which is deeply 

 emarginate, the remainder equal ; the scape yellow beneath, as 

 \vell as the second joint or pedicel ; the swollen portion of the 

 fourth and the margin of the fifth fulvous, the seventh, ninth 

 and eleventh joints white ; the clypeus more produced ; the 

 ridge at the lower margin of the cheeks forming a tooth ante- 

 riorly, near the mouth ; the coxae and trochanters of the inter- 

 mediate legs and the base of the coxae and the trochanters of 

 the posterior pair yellow ; the apex of the intermediate tibiae 

 yellow; the basal joint of the anterior tarsi dilated on the inside, 

 that of the intermediate pair on the outside in the middle, the 

 posterior pair slightly curved, flat beneath, and all of them fim- 

 briated at their sides ; the posterior femora very pubescent 

 beneath. 



This species is rarely taken in the London district, but being 

 one of those insects which burrow into the pith of brambles 

 and rose-branches, is more readily to be obtained by collecting 

 such sticks in the spring ; by these means many apparently rare 

 species are to be obtained in plenty. This insect usually appears 

 in June : Hedychrum ardens is parasitic upon it. 



B. Div. 2. Abdomen subpetiolated. Ocelli in an equilateral 

 triangle. Antenna and tarsi simple. Base of the meta- 

 thorax smooth and shining. (Sp. 3, 4.) 



3. Crabro dimidiatus. 

 C. niger, flavo-maculatus ; abdomine petiolato. 



