42 



Colonel Yerbiirj' and Mr. W. R Ogilvic Grant took, in addition tn 

 the normal male already mentioned, three females of the bisignatits 

 form. In many of the females in the Museum collection there is no 

 trace of the russet markings on the sides of the second abdominal 

 segment seen in the specimen shown in the plate, but the abdomen 

 appears wholly black, with, however, a longitudinal row of whitish 

 markings on each side of the median series of white triangles. The 

 resemblance between the form bisiguaius and TheriopUctcs iiikans, 

 Mg., has already been alluded to in the notes on the latter species 

 (see page 7,y). 



The two males of T/i. tropicus referred to above are 145 mm. in 

 length, with a wing-expanse of 28 mm. ; the length of the females 

 varies from i4to iSjmm. According to Brauer {loc.cit., pp. 146-147) 

 the eyes in this species are green with three purple bands ; in the 

 male the lower margin is green and unbanded. The Museum pos- 

 sesses no specimens of this species from Wales, Scotland, or Ireland, 

 but in England at any rate Tli. tropicus appears to be among the 

 more common of the larger horse-flies. The dates of capture of the 

 females in the Museum series range from Ma\' i6th to July 12th inclu- 

 sive, and the localities are Brinklow, Warwickshire {E. E. Austen); 

 Berkhamsted, Herts ( W. R. 0. Grant) ; Feldcn, Boxmoor, Herts 

 {A. Piffard); Colchester, Essex ((/'. //. Haruood) ; Oxshott, Surre\- 

 ( //'. R. 0. Grant and Lieut.-Colonel Yerhurr) ; and New Forest, Hants 

 [Lieut.-Culonel Yerbury and C. 0. Watcrhouse). In the last-mentioned 

 locality Colonel Yerbury notes that bisignatus is the common form of 

 the S[jecies. Continental sjjecimens of Tli. tropicus in the Museum 

 collection are from Siberia, Norway and Russia (typical form), and fmm 

 Rhenish Prussia (form bisignatus). Additional Continental localities 

 given by Brauer are Sweden, Germany and Austria for the t\-pical 

 form, and France, Silesia and Asiatic Russia for the form bisignatus, 

 which was originally described from a specimen from the neighbour- 

 hood of Paris. 



