LAMB— DIPTERA : LONCH^ID^, SAPROMYZID^, EPHYDRID^, ETC. 341 



sides are slightly convex, and the rounded apex extends nearly to the base of the 

 antennse : two side triangles are thus formed between the eye-mai'gins and the triangle 

 which are duller than the central triangle and slightly purplish in colour. Five fronto- 

 orbital bristles, one vertical, crossed post- verticals, parallel ocellars. The face below the 

 antennfe and rio-ht up to the mouth margin is deeply recessed, the bottom of this pit or 

 recess is paler than the rest and is sometimes quite yellowish. The mouth margin and 

 hind head are shining black. The large sparsely pubescent eyes occupy nearly the whole 

 of the head in side view (PI. 16, fig. 1'-^). The mouth margin is finely bristled, the 

 bristles being of nearly equal size. Tongue, black, horny with a backwardly bent 

 yellowish tip. Palpi black or blackish. 



The antennae are black, the thiixl joint large, orbiculax and pubescent; arista 

 black and strongly pubescent. 



Thorax. Very shining black with fairly long bristly hairs on the dorsum, bent 

 backwards, the last dorso-centrals present. Scutellum also shiny black with two end 

 bristles situated a little dorsally of the rounded margin. Metanotum black and very 

 shining. 



Fig. 26. Oscinis oculata, n. sp., wing. Fig. 27. Oscinis oculata, ii. sp., var., wing. 



Wings: the normal form is as shown in Fig. 26, the axillary lobe being well 

 developed and the wing of normal outline. The second vein is always gently bent up to 

 the costa, the third and fourth veins are quite parallel in their distal portions. In other 

 specimens (which are in other respects indistinguishable) the wings are different in form. 

 In some the wings are of the shape given in Fig. 26, but are proportionately shorter; 

 while the normal wing has its lens:th about 2-4 times the maximum breadth, in the 

 present case the ratio fells below 2-3: this form has usually slightly darker legs than the 

 typical form. A more extreme form occurs in which the shape of the wing is altered, 

 as shown in Fig. 27: the axillary lobe is smaller, and the wing is more "bat" shaped; the 

 above ratio has here a value of 3 to 1. All the forms occur together, and are more 

 or less connected by intermediates. It is possible that the form figured in Fig. 27 is a 

 distinct species, although in other respects it is practically identical with the normal type. 

 The veins are brownish. 



Halters pale. 



The legs are also slightly variable in colour; in most cages they are yellow with 

 various degrees of infuscation. The commonest form is as follows: front legs (including 

 coxae) yellow; middle legs, cox;b black, femora very slightly infuscate on the distal half 



