MICROPTBROUS FLY. 87 



Head. — The head is large and broad, depressed as a whole, but 

 with both the dorsal and the ventral surfaces convex ; no lateral 

 surface can be distinguished. As viewed from above, the outline 

 is rounded in front and truncated posteriorly, the sides being 

 nearly straight. The anterior third, as seen from the side, is 

 deeply concave, and is occupied by the antenna, the third joint of 

 which is of great relative size and spherical in form, entirely con- 

 cealing the first and second joints ; near its apex it bears a very 

 long and slender minutely pilose arista. The lower margin of the 

 antennal cavity forms a sharp ridge which is produced forwards, 

 just in front of the eye into a triangular projection. The eye is 

 small and appears to be pigmented very little if at all more deeply 

 than the surrounding integument ; it consists of about twelve 

 facettes, which are by no means prominent, and is situated laterally 

 but below the margin of the head, being narrowly oval in outline 

 and horizontal in position. The palpi are large and conspicuous, 

 somewhat irregularlj^ club-shaped in form and armed with four 

 large bristles on the inner margin and at the tip, being also sparsely 

 clothed with minute recumbent hairs. The proboscis is very long 

 and slender, and, except at the base, has a cylindrical form through- 

 out its length. It is divided into three unequal regions : (1) A 

 short flat triangular region lying on the ventral surface of the head 

 between the palpi ; (2) a proximal cylindrical portion which is the 

 longest, running parallel to the base of the sternum nearly as far as 

 the coxae of the intermediate legs : it is separated from the third 

 region by a distinct band. The third region (3) points downwards 

 and backwards between the legs. There are a few minute and 

 apparently soft hairs at the tip, but only very small and ill-developed 

 fleshy expansions ; no trace of any organ that could be used for 

 stabbing or cutting is apparent. 



The whole of the dorsal surface of the head is covered sparsely 

 with minute recumbent hairs, all of which point backwards. There 

 are about twelve small forwardh' directed bristles on each side of 

 the ventral surface below and behind the eye. On each side of the 

 head there are three much larger bristles, all of which are directed 

 forw^ards. One is situated just in front of the eye, another outside 

 each palpus, and the third near the posterior end of the ventral 

 surface of the head beside the proboscis. The direction of the two 

 latter is somewhat obHque. 



The integument of the head is minutely and regularly punctured, 

 but that of the proboscis is smooth. 



Thorax. — As seen from above, the pronotum, which conceals the 

 other segments, is longer than the head, but distinctly transverse. 

 It is divided longitudinally by a deep mid-dorsal groove, and near 

 the anterior border on each side there is a small circular pit. A 

 comparatively large chitinous plate on the dorsal surface of the 

 abdomen, narrowly separated from the posterior margin of the 



