5. DYSMACHUS 663 



its end (makin.t,' it appear punctate), while tlie second piece is more than a 

 tliird the length of the first and also bears dense minute bristles ; the terminal 

 lamellae are inserted like a wedge between the two end points of the outer 

 upper piece, but the lower one of these two points is so long and narrow as to 

 be easily overlooked ; the large under piece is as long as the upper pieces and 

 bears very dense short bristles on its end part ; pubescence rather long and 

 pale beneath near the base, and rather abundant short and pale beneath the 

 terminal lamellae. 



Length about 13 mm. 



This species varies very much in the colour of the pubescence and 

 bristles, and in the amount of reddish colour at the base of the tibiae, 

 while I believe it has a tendency to develop into local races. A male 

 taken by Colonel Yerbury at Christchurch on July 4, 1897, looks very 

 distinct, as it is larger and has a longer straighter abdomen and I suppose 

 the straifrhtened-out abdomen causes the hindmarcrins of the second to 

 fifth segments to be widely bare and when seen from behind to appear 

 more blackish grey and in no light conspicuously light grey ; this specimen 

 (which is probably over-mature) has other pecvdiarities, the basal joint of 

 the antennae being not longer than the second, and the junctions of the 

 basal and second joints and conspicuously of the second and third joints 

 being ferruginous, while the basal joint has long stiff black bristles 

 beneath and only very slight yellow bristles dorsally, the bristly middle 

 line of the thorax is darker than the sides of the middle stripe, and the 

 side stripes extend further forwards without being disturbed by the 

 humeral stripes, so that there is no light grey space in front of the side 

 stripes, the innermost (towards the disc) prsesutural, supra-alar, and 

 postalar bristles are black, the seventh abdominal segment has no hind- 

 marginal bristles, the claspers seem to be broader in proportion to their 

 length, the postero-ventral hairs on the front femora are so strong as to 

 be practically bristles, the postero-ventral hairs on the middle femora are 

 almost all black, the hind tarsi have no black bristles on the apical 

 circlets of the joints, the wings are conspicuously orange about the base, 

 and the base of the costa bears some obvious pale hairs, while the 

 squamae and their margins are orange; another male taken by me at 

 Felixstowe in Suffolk is peculiar, as it has scarcely any pale hairs on the 

 hind part of the disc of the thorax or on the disc of the scutellum, while 

 the black hairs on the face-beard and the black bristles on the underside 

 of tlie basal joint of the antennae are more numerous, and several of the 

 supra-alar and postalar bristles are black ; a male taken at Southbourne 

 (which is in the same district as Christchurch) on August 10, 1904, has a 

 strong tendency towards the Felixstowe specimen but appears very 

 different from the Christchurch specimen. My description has been 

 mainly made from a number of sj)ecimens taken at Barmouth (in which 

 the pale bristles and hairs are unusually whitish) ; continental specimens 

 practically agree, but may differ a little in the bristles on the legs. 

 D. trir/onus belongs to a small group of about five very closely allied 

 species which have the thoracic middle line with conspicuous mane-like 

 bristles almost up to the front, no bristles beneath the front femora, the 

 male genitalia short and simple, and the female ovipositor sabre-shaped, 

 but none of the other species are likely to occur in Britain as they are only 

 known from Spain. Its squat figure and numerous conspicuous white 

 bristles distinguish it at once from any other British species of the Asilince, 



