326 Transactions. 



reach quite to the posterior margin except where they are continued round 

 the posterior angles and extend for a short distance as a spot on each side 

 along the anterior margin of the 3rd segment ; the tawny vestiture, also, 

 is more distinct and forms orange-yellow hair most conspicuous along the 

 sides of 3rd and 4th segments ; in some cases the tawny areas of the 2nd 

 segment may be confluent with those of the 3rd over the posterior margin 

 of the former segment ; there may also be a small tawny spot at anterior 

 angles of 4th segment. All the known specimens of this variety are from 

 the Chatham Islands. The development of the abdominal spots and the 

 conspicuous orange-yellow vestiture tend to show that this variety is 

 intermediate between the $ and $ antipodus. 



The male of antipodus differs from the female in the following : 

 Vestiture of face longer ; posterior femora rather broader ; apical markings 

 of anterior and middle tibiae less distinct ; abdomen with a more conspicuous 

 vestiture and the 3rd segment with a distinct pair of tawny spots (fig. 71) ; 

 tawny areas of 2nd segment much broader than $, thus resembling those 

 of var. vincinus $ ; the indistinct greyish-black spots of 4th segment pre- 

 sent as in $. Genital segments (figs. 72 and 73) blue-black, the genitalia 

 tawny. 



$. Length, 11-12 mm. $. Length, 13-15 mm. $. Length, 14 mm. 

 (var. vincinus). 



Plesiotype : No. 977, D. M. Syn types : Var. vincinus, Hutton's col- 

 lection, Canterbury Museum. 



Habitat. — Throughout New Zealand ; Campbell Islands ; var. vincinus, 

 Chatham Islands. 



H. trilineatus Fabricius. 



Syrphus trilineatus Fabr., Syst. Ent., p. 766 (1775). Eristalis tri- 

 lineatus Fabr., Syst. Anil., p. 238 ; Wied., Auss. Zweif., ii, p. 168 

 (1830). Helophilus trilineatus White, Voy. "Erebus " and "Terror," 

 Ins., pi. 7, fig. 19 (1874) ; Walker, Cat. Dipt. Brit. Mus., p. 607 

 (1848) ; Hutton, Cat. Dipt. N.Z., p. 41 (1881) ; Trans. N.Z. 

 Inst., vol. 33, p. 38 (1901). 



A fly closely resembling antipodus, but more robust and much larger. 



$. Differs from antipodus in the following characters : Eyes more 

 approximated, the black of upper front, vertex, and ocellar triangle per- 

 manent in all lights only on the triangle, the yellowish-brown of lower 

 front being reflected over upper front and vertex, thus forming brownish 

 mottlings in some lights ; transverse band across antennae broader at 

 frontal lunule ; vestiture of front and vertex short ; oral margin broadly 

 margined with blackish brown, which is not upturned to any extent along 

 anterior margin ; oral margin not distinctly notched in front (fig. 77) ; 

 cheeks cinereous to pale yellow and clothed with whitish hairs ; occiput 

 cinereous. 



Median black stripe of thoracic dorsum not narrowly spilt anteriorly ; 

 upper two-thirds of pleurae cinereous-yellow ; scutellum black in some 

 lights but otherwise as in antipodus. Anterior and middle femora blue- 

 black on basal half, otherwise orange-red ; posterior femora altogether 

 blue-black, very much broadened to a bristly prominence distally below, 

 and with a stout spinose tooth below near base (fig. 74) ; around this 

 tooth and distal prominence of posterior femora orange-red, and the lower 

 side distinctly spinose ; anterior and middle tibiae and all the tarsi 

 orange-red ; posterior tibiae orange-red but for a broad blue-black area 

 at base, and with a distinct apical tooth below. 



