466 CYRTID.E 



of the costal and subcostal veins less distinct. Squamae whiter. Halteres 

 orange. 



Length about 4-5 mm. but very variable in size in both sexes (3-5 to 

 5-5 ram.), some specimens being three or four times as large as others. 



This species varies considerably in size in both sexes but especially in 

 the male, and in the extent of the bone-white bands or markings. It is 

 easily distinguished from its allies by the pale glassy squamse which have 

 no dark margins, by the partially black femora, and by the absence of any 

 darkening on the wings. 



0. gihbosus seems to be a fairly common New Forest fly in June and 

 July, as I have taken it there myself hovering or floating high up in the 

 air, and I have seen a large number of specimens from there ; I have also 

 seen specimens from Herefordshire taken by Colonel Yerbury in the 

 Golden Valley and by Dr J. H. Wood at Woolhope. Mr Claude Morley 

 has recorded it from Barnby Broad in Suffolk, and there is a male in the 

 Hope Museum at Oxford labelled as from Eichmond Park on July 4, 1835. 

 Curtis said that it was taken " in May and June on Wimbledon Common, 

 " and in Coombe Wood," while he said of his Hcno2:>s /nanjinatus (which 

 was almost certainly the female of 0. (jibhosus) from the New Forest, " My 

 " specimens I purchased of the late Mr Joseph Standish, who beat them 

 " out of old white thorn bushes that were covered with lichen, the end of 

 " June and beginning of July. They were so sluggish in the net that 

 " they laid with their wings closed, which made it difficult to detect them ; 

 " and the least pressure destroyed the rotundity of their bodies, which are 

 " very thin, and with the large wings and scales appear to be well adapted 

 " to enable the insect to float like a balloon in the air, subject to the 

 " influence of any current that may prevail." The few certain dates that I 

 know range only from June 26 to August 5, and I may note that all the 

 males were taken in June or July but all the females in August. The 

 remarkable fact recorded (Entom. Month. Mag., xxxviii., 205, 1902) by 

 Rev. H. S. Gorham as to the storing of upwards of fifty specimens of this 

 fly in a hollow thistle (Cnicus palustris) stem by Crabro interruptus at 

 Emery Down in the New Forest shows that the species must be common 

 or at least locally abundant, and his statement that there is a mimicry 

 between them and the spider they prey upon makes a closer study of their 

 habits most desirable. It is recorded from Central and Northern Europe. 



Synonymy. — It is almost certain that Curtis' figure and description of Ileimps 

 Tuiarginattis refer to this species, as his statement "Legs dull ferruginous, fuscous 

 " towards their base " could not apply to 0. pallipes, and I am confirmed in this 

 opinion by a female in the Hope collection at Oxford labelled " marginatus." 



2. O. pallipes Latreille. Squam?e smoky, with blackish margins. 

 Halteres black. Wings with the foremarginal veins blackish, but with 

 no dark clouding. Legs entirely pale luteous. 



Very much like 0. gibhosus, but easily recognised by the 

 diagnostic characters. 



$ . Longer in proportion to its width and less bladder-shaped than 0. gihbosus. 

 Head almost as in 0. gibhosus. Eyes with the dividing line running from the 

 back across the middle almost absent, though some irregular facets show 

 where it might be. 



