1. THEREVA 561 



yellow to tawny or reddish yellow through various shades to greyish white, 

 so that the term " ferrugineo-hirta " as used by Zetterstedt is not always 

 quite correct, though it is approximately so in contrast with " ohscAire 

 " hirta " as applied to T. plebeia. As to the allied British species ; T. 

 hipunctata is smaller and may be at once distinguished by the more 

 whitish colour on all parts, by the apparently wholly whitish {not 

 white) haired abdomen (when viewed from behind), and by the more 

 emphasised veins when seen from the wing-tip ; T. plchcia is more difficult 

 to distinguish in the male, but has the thorax of a blacker hue and the 

 abdominal pubescence (when viewed from behind) apparently all dull 

 yellowish beneath and all black above, with the sides of the abdomen 

 whitish rather than light brownish grey and the black bases of the 

 segments less suddenly widened at the middle ; T. circumscripta is a 

 darker species with an appearance of much blacker pubescence generally ; 

 T. arcuata (if my species be correctly named) has the ground colour of the 

 abdomen deep black with cinnamon bands and usually brilliant alternate 

 foxy red and black pubescence, but I cannot well distinguish Loew's 

 character of a brownish arc over the end part of the discal cell. The 

 female of T. nohilitata is more easily distinguished from its allies but 

 varies in the size of its frontal callus (which is never so large as in T. 

 plcheia), which may be very small and even occasionally divided into two 

 spots (when I am bound to consider it to be the T. ocidata of Egger), but even 

 then these spots do not show any relationship is to T. hipunctata which 

 is a smaller species with a much more yellow haired seventh abdominal 

 segment ; a specimen taken by Colonel Yerbury at Barmouth on June 26, 

 1902 has the frontal callus separated into two small spots which are well 

 isolated as they are well apart from each other and from the eyemargins, 

 and this same specimen has the frons brown with the black pubescence on 

 the fore part rather extended and has its fifth and sixth abdominal segments 

 yellow haired at the sides ; I have seen a female with two prsescutellar 

 bristles on one side but only one on the other; the abdomen varies con- 

 siderably in the distinctness and extent of the basal black bands though 

 they are always much narrower than in T. plcheia, and it also varies in 

 individual specimens in the extent of the black pubescence until in a 

 small female taken by Colonel Yerbury at Derrynane in Kerry on July 

 21, 1901, the fourth segment bears numerous erect black hairs mixed with 

 the recumbent yellow pubescence and has all the hairs on the fifth to 

 eighth segments erect and black, while it also has the wings absolutely 

 unclouded ; on the other hand I have seen a specimen with the seventh 

 abdominal segment almost all yellow haired, and any black pubescence on 

 the abdomen very slight; two specimens taken by Colonel Yerbury at 

 Nethy Bridge on July 7, 1903, are small and have the last four (especially 

 the last three) segments black haired and with distinct black bases on the 

 fifth and sixth segments, while in both specimens the fourth posterior cell 

 is wide open ; this latter character however is not uncommon, and some- 

 times a specimen may have the cell open in one wing and closed in 

 the other, while on the other hand this cell is sometimes distinctly stalked ; 

 a male taken by Mr F. Jenkinson in his garden at CamlDridge on 

 August 10, 1903, has the lowest veinlet from the discal cell of the right 

 wing broken off at half its length but becoming visible again at its end in 

 the wingmargin so as to show that the fourth posterior cell would have 



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