556 THEREVIDiE 



taken it myself, but Colonel Yerbury has given me five specimens 

 (26, 3$), and the Cambridge Museum has about five others taken by 

 Mr F. Jenkinson, who once caught a pair in coitu and who watched two 

 females at Forres which were laying eggs in dry soil. 



Synonymy. — I record tliis species as T. arcuata Lw. because there is no other 

 German species described in Loew's Beitrage ii. which can possibly be it, and I 

 cannot believe that it was unknown to him. Further corroboration is given 

 through Loew's statement that T. arcuata is exceedingly variable in the colour 

 of the pubescence, and I think it was the only species in which he spoke of 

 the pubescence on the abdomen being sometimes " rothgelb, fast fuchsroth " ; 

 amidst all its variations however he gives as an unfailing character, " arculus 

 " inf uscatus a nervulo transverse ordinario trans finem cellulse discoidalis ductus," 

 and unfortunately I am unable to clearly recognise that character in our British 

 specimens ; nevertheless in viewing the wing from the wing-tip (whereby the wing- 

 markings become most clearly defined in all species of Thereva) I think this arched 

 cloud can be traced ; Loew however does not seem to have met with any specimens 

 in which the tarsi were so extensively black as in my description. I cannot trace 

 this species at all in Zetterstedt's writings unless he mixed it up with T. nobilitata, 

 .nor does it occur in his collection at Lund. Thereva alhilahris and T. flavilabris 

 Meig. may include it, but unfortunately the types were out on loan when I examined 

 the Paris Museum in 1906. 



Var. inornata. Pubescence light grey or greyish yellow instead of 

 bright tawny. Tarsi as ferruginous as in the allied species. 



6. Described from two si^ecimens only. Pubescence light grey to greyish 

 yellow (when pale) on the face, jowls, loAver part of back of head, and 

 pleurae, but in one specimen becoming rather tawny but not foxy tawny on 

 the upper i^art of the back of the head and on the disc of the thorax, and 

 pale brownish yellow on the abdomen until the much less conspicuous out- 

 standing black hairs are reached ; in the other specimen the pale abdominal 

 pubescence is grey (not at all tawny), but (when seen from above) with 

 numerous black hairs outstanding at the basal corners of all (including even 

 the basal) segments ; pubescence on the disc of the thorax and on nearly all 

 the disc of the scutellum extensively black in one specimen. In the male 

 (Aviemore, June 18, 1899) which has a tendency towards tawny pubescence 

 the black markings on the abdomen cover about the same space as in the 

 typical T. arcuata but are less defined and the lighter spaces are greyish or 

 greyish yellow (not greyish orange), and in some lights this greyish yellow 

 coloring becomes much more extensive on the fourth segment and thence 

 to the tip of the abdomen, in fact very much so when viewed from behind. 

 Pubescence on the anterior femora greyish brownish yellow with a slight 

 admixture of black hairs near the tip, — in typical T. arcuata this pubescence 

 is black and apparently more dense ; — hind femora with the pale scales more 

 numerous than in the typical T. arcuata ; tarsi with all the basal joint except 

 its tip, and the base of the second joint, brownish yellow. 



9 . Pubescence and dust grey with a slight yellowish (not tawny) tinge. Frontal 

 callus small and rather more emarginate in front. Hind femora, as in the 

 male, but with more numerous grey scales. Stigma yellower. In a second 

 female the pubescence is rather more orange. 



I have seen two males of this form which were taken by 

 Colonel Yerbury at Aviemore on July 10 and 18, 1899, and one or two 

 females taken by him at Golspie in July 1900. He also took a female at 

 Golspie on August 18, 1900, which I consider to belong to true T. arcuata 

 and another female in July (which however may be only T. noHlitata) 

 and a female at Nethy Bridge on July 29, 1904, in which the frontal callus 

 is small and narrow. The chief distinctions of inornata from typical 



