3. RHADIURGUS 649 



This species is one of our largest and handsomest British flies, and has 

 no ally in Europe except the Mediterranean A. larharvs. 



A. rriibroni/ormis is much more common in the soulhern part of 

 England than is commonly imagined. It may seem strange but it is 

 nevertheless true that so large and conspicuous an insect is not easily 

 seen ; on commons or pastures it flits from bare patch to bare patch 

 without waiting to be closely approached and harmonises very much 

 with the ground upon which it rests. I have records from Cornwall 

 (The Lizard and St Ives), Devonshire (Plymouth, Holne, and Tor Cross), 

 Dorset (Canford Common, Swanage), Hampshire (Lyndhurst, Bourne- 

 mouth, and Freshwater in the Isle of Wight), Sussex (Eastbourne, Lewes, 

 etc.), Sullblk (Newmarket, where it used to occur in a pasture which is now 

 part of my garden,* Fritton, Tostock, Assington Thicks, and Bentley 

 Woods), Berkshire (Tubney), Oxfordshire (Shotover, etc.), the neighborhood 

 of Bristol, and according to B. Cooke the Cheshire coast, while in many 

 of these localities it is comparatively common. It preys on remarkably 

 large insects, as I saw it feeding on Scricomyia borcalis and on a very 

 large Sarco2)haf/a carnaria on Canford Common in August 1904. My 

 dates make it out to be a rather late species as they extend from July 

 18 to September 30. It is recorded from all Europe and the greater 

 part of Asia, while Walker (probably incorrectly) recorded it from 

 Australia (List. Dipt. Brit. Mus. Suppl. 680) though a specimen from Bigot's 

 collection is labelled " New Holland." 



3. RHADIURGUS. 



Ehadiurgus Loew, Linn. Ent., iv., 133 (1849). 



Greyish black fliies of rather small size, distinguished from 

 all other Em'opean Asilinw by the shining black face. 



Face shining black, with whitish eyemargins and with whitish tomentum on 

 the facial knob ; facial knob large and well defined ; face-beard bristly ; postocular 

 festoon well developed, but the stout bristles not long and not much bent forwards 

 at the tip ; f rons at the vertical part rather deeply sunk between the eyes and the 

 oceUar knob correspondingly elevated, moderately wide but not widening out at 

 all at the upper eye-angles. Antennal style long and rather thin. 



Thorax with the ordinary short pubescence all well distinguished from the long 

 bristles ; dorso-central rows of bristles ending anteriorly abruptly just in front of the 

 suture ; metapleural and hypopleural fans fairly distinct. Scutellum clothed with 

 inconspicuous soft upturned pubescence, and with from two to four upturned 

 marginal bristles. 



Abdomen rather flat, unusually bare and without any bristles against the hind- 

 margins exceijt a few indistinct ones near the sides of the basal segment ; eighth 

 segment of the male concealed dorsally, but short and simple ventrally, concolorous 

 with the preceding segment. Genitalia of the male long but not knobbed ; claspers 

 with a large strong tooth on the inner side ; penis most unusually long ; ovipositor 

 short, blunt, and conical or rather depressed, but in no way laterally compressed, 

 ending in a pair of ovate lamella and without any terminal circlet of spines ; eighth 

 abdominal segment of the female depressed and appearing to form the base of the 

 ovipositor. 



Wings normal. Alar squamae with only moderate fringes. 



Legs moderate in shape and length, black with the tibi^ and tarsi partly 

 dull red. 



* A specimen was seen on September 3, 1908, after a lapse of about twenty-eight years. 



