3. OXYCERA 97 



principal variation I have seen is caused by the presence of a pair of small 

 yellow spots on the disc of the thorax of the male, each spot being well 

 isolated and placed just behind the suture, and one such specimen was 

 taken by Mr C. Morley at Barnby Broad in Suffolk on July 2, 1904, and I 

 have seen a second similar specimen. My description has been made 

 from quite freshly killed specimens, but in dry specimens the yellow 

 markings usually become orange. 



0. formosa occurs in rather numerous colonies, each colony occupying 

 a very small space, in a few localities in England. I have records from 

 Dorset (Glanville's Wootton), Hants (Woolmer Forest), Sussex (near 

 Lewes and at Guestling), Surrey (near Eeigate ?), Suffolk (on Fteris and 

 flowers of Spircea ulmaria at Foxhall, taken by Mr C. Morley), Norfolk 

 (Wroxham), Cambridgeshire (in Willow Beds near Whittlesford, and in 

 Chippenham Fen in wet spots on the drive through the Forty Acre AVood), 

 Glamorganshire (Porthcawl in abundance), and of course in several locali- 

 ties in Herefordshire. Dr Wood states that it occurs on marshy bogs or on 

 the sedgy margins of old silting-up pools. My records extend from June 

 23 to August 10. It is recorded from many parts of Europe, extending 

 southwards to Italy but apparently not further north than South Sweden. 



Synonymy.- — Meigen originally described this species from details sent to him by 

 Wiedemann, but at the same time described it as 0. mnscaria Fabr. in more detail 

 and from personal knowledge ■ he subsequently (Syst. Beschr., iii., 346) discovered 

 this synonymy and corrected Ms mistake, but at the same time fell into another 

 mistake by stating that his 0. pygmcea was the true 0. muscaria Fabr., while all the 

 time 0. muscaria of Fabricius was an Italian species of which O.Jiavi2)es Loew is 

 probably a synonym. 



5. O. tenuicornis Macquart. Cubital vein forked. Antennse remark- 

 ably elongate and without any terminal style (fig. 114). Legs all black, 

 except at the front knees {6), or with at least the apical half of the front 

 tibise and all the front tarsi black (?). 



A very distinct species, because of its long antenna; which 

 apparently have no terminal style. 



c? . Face and f rons forming a rather flat shining black triangle ; face with rather 

 broad whitish bands down the sides, upon which there is a very short 

 inconspicuous whitish pubescence, but upon the rest of the face there is a 

 fairly abundant erect black pubescence ; face in profile slightly prominent 

 in front of the eyes, but its lower part almost flush with the eyes, as is 

 also the front part of the jowls, and the whitish sides of the mouth are 

 very narrow; back part of the jowls and lower part of the back of the 

 head distinctly inflated and moderately shining black, and the pubescence 

 on the lower part of the jowls and all about the back of the mouth 

 longer and rather conspicuously greyish white, but the upper half of the 

 back of the head almost flush with the eyes and bearing a short dense 

 black stubby postocular ciliation ; vertex shining black, considerably elevated, 

 and with only short and slight black pubescence. Eyes bare (sparse micro- 

 scopical hairs occur), practically touching for abnost half the distance between 

 the occiput and the antennte ; facets on more than the upper half large and 

 (in death) pale reddish brown, but the small facets on less than the lower 

 half blackish, and the contrast between the two rather sharply defined. 

 Antennae dull blackish, very long, being as long as the head itself in 

 profile ; two basal joints short and bearing tiny black bristles ; third joint 

 practically bare and formed of six distinct annulations, of which the last one 



