568 THEREVID^ 



on the face, exclusively black hairs and two visible stripes on the 

 disc of the thorax, and the pubescence on the abdomen not sharply 

 differentiated in colour though whitish ventrally; a third male taken in 

 company with the other two is less distinct but also has stripes down the 

 thorax, narrow hindmarginal hems on the abdomen, and the ventral 

 pubescence all yellow. The females (though usually rather regular in 

 size) may vary from 9 mm. (Denmark Hill, London, June 21, 1867) to 

 12 mm. (Bunker's Hill, near Lewes, June 5, 1870). The male is often 

 difficult to distinguish from those specimens of T. nohilitata in which 

 the black pubescence predominates, but in my opinion is a slightly 

 narrower blacker insect (especially about the base of the abdomen) in 

 which the abdominal pubescence (besides beiug rather abruptly contrasted 

 in colour dorsally and ventrally) has the pale hairs without any tawny 

 hue, while ordinarily only a few inconspicuous light colored hairs extend 

 over the sidemargins on to the fore corners of the second abdominal 

 segment. The female can easily be distinguished from T. nohilitata by 

 the large and conspicuous black bands on the abdomen, by the much larger 

 frontal callus, and by the short rigid black abdominal pubescence which 

 commences on the fourth segment. T. arcuatu var. inornata is not always 

 easily distinguishable in either sex, but the male is narrower and has the 

 fulvous or greyish pubescence more extended up on to the disc of 

 the basal abdominal segments while the clump of black hairs below the 

 eyes is less distinct, and the female has a much smaller frontal callus 

 which does not extend up at all near the front ocellus, less numerous 

 black hairs below the eyes, the abdomen much more covered with pale 

 pubescence and broader grey bands, the thorax more distinctly striped, 

 and the fifth and sixth abdominal segments less black haired. My 

 description has been made from about fifty British specimens, but amongst 

 them were only about a dozen males in good condition, and it is only 

 on one occasion that I have known a number of specimens to have been 

 taken in company and they were all females. 



T. pleheia is not an uncommon British species and is one that may 

 occur in gardens, where it is not quite so common as T. nohilitata, though 

 I have taken it both here and at Denmark Hill, while Mr F. Jenkinson 

 has taken it rather freely in his garden at Cambridge. I have numerous 

 records from almost all the southern counties from Cornwall to Kent, 

 and from Suffolk, Cambridgeshire, Oxfordshire, Bucks, Worcestershire, 

 and Herefordshire, while I believe I have seen it from Eannoch and 

 Golspie. It is worthy of note that when Colonel Yerbury was taking 

 very large numbers of T. nohilitata and T. hipvndata at Porthcawl he 

 did not take a single specimen which could by any possibility be con- 

 founded with T. vlcheia. The dates range from Mav 13 to August 15. 



Synonymy. — Of course T. pleheia cannot be fully identified by any of the older 

 descriptions though Linne's description almost fixes it and by tradition the present 

 species has been accepted as the exponent of his name ; Loew however called it 

 T. lugens and said that it commonly occurred in collections under the name of 

 T. lugnhris. Walker's description of T. pleheia cannot possibly apply to this species 

 but probably to the female of T. nohilitata. A very small female of this species 

 which I sent to Loew was returned as " Thereva sp ? nr, lugubris." 



5. T. circumscripta Loew. Eather large species, normally with darkened 

 wing-veins. Male with unusually predominant black pubescence, and even 



