I04i MANDIBULATA. IlYMKXOl'TEUA. 



Cephas differs chiefly from Janus by having the antenna distinctly 

 clavate ; the neuration of the wings is aKo discordant ; the abdomen 

 of the males more cylindric, not being dilated towards the apex, 

 which is obtuse, and in the females that joint is considerably com- 

 pressed towards the tip, and the ovipositor is exserted : the penulti- 

 mate joint of the palpi is very small, and is frequently produced on 

 one side, a character that does not appear to have been previously 

 noticed : the species frequent flowers. 



Sp. 1. Troglod}''ta. Aier nitidus, ahdomine punctls aliquot fasciis(jue duabus 

 Jlavis, alis stigmate testaceo. (Long. corp. 6 lin.; Exp. Alar. 10 lin.) 



Li. Troglodyta. Fabricius. — Sy. niger. Harris Ex.pl. xxviii.J". 2. — Ce. Tro- 

 glodyta. Steph. Catal 341. No. 3982. 



Black;, shining : mandibles yellow in the middle^ the apex ferruginous; thorax 

 with a small yellow dot on each side beneath the wings, and a larger 

 triangular one of the same colour on each side of the metathorax ; abdomen 

 with a large triangular yellow patch on the basal segment, a minute yellow 

 dot on each side of the margin of the 2nd, the 3rd and 4th each with a 

 broad marginal yellow band, 5th immaculate, 6th with a very broad marginal 

 band, the 7th with an interrupted one, both yellow; legs black; tibiae and 

 tarsi pale testaceous, the hinder tibiae with the apex black; wings hyaline, 

 iridescent, nervures ferruginous, stigma testaceous. 



It varies in having the fasciae on the abdomen more or less obscure, and in 

 having the posterior tibiae entirely pale testaceous. 

 Scarce : taken occasionally at Hertford, and in other places within 



the metropolitan district, about the end of June. 



Sp. 2. quinque-fasciatus. Ater nitidus, collaris margine ahdomiiieque fasciis 5, 

 tihiis tarsisque totis, Jlavis, alis stigmate fiavescente. (Long. corp. 6\ — 7 lin.; 

 Exp. Alar. 9|— 11 lin.) 

 Ce. 5-fasciatus. Steph. Catal. 341. No. 3983. 



Shining black: head with a minute angulated yellow mark between the 

 antenna; on the clypeus, and a dot of the same on the inner orbits on the 

 crown ; thorax with the margin of the collar yellow, and a spot of the same 

 on each side of the metathorax ; abdomen with a triangular patch on the 

 1st segment, the 3rd, 4th, 6th, 7th, and 8th segments with a broad entire 

 marginal band, and the 2nd and 5th with a minute dot on each side, all 

 yellow ; legs black, with the extreme apex of the femora and the tibiae and 

 tarsi entirely yellow; wings hyaline, yellowish, with the nervures and the 

 stigma brighter. 

 Male with the front of the head luteous, with a spot on the clypeus, and a 

 streak on each side and at the base of the mandibles black, the 2nd segment 

 of the abdomen immaculate, and the abdomen itself linear. 

 Taken in the west of England, near Bristol, I believe, but appa- 

 rently very rare, in the beginning of June. 



