492 



Messrs. N. A. Cobb and A. S. OllifF on 



rior margin of the first thoracic segment ; but this is not 

 really the case. The appearance is deceptive, and is merely 

 due to the fact that the " supplementary segment," or, more 

 correctly, the hinder division of the head, is partly withdrawn 

 into the first thoracic segment. Our larva has the protrusile 

 labium which is common to all the species of the family, 

 and the anal segment of the body is provided with a retrac- 

 tile organ, wdiich probably assists the larva in locomotion. 

 We did not observe that this particular larva possessed the 

 power of jumping, as some of its allies are said to do. When 

 yonng the specimens were dull white in colour, but afterwards 

 they turned to a bright orange-yellow. In the latter state 

 they measured If millimetres ; but perhaps they were scarcely 

 full-grown. 



In explaining, more particular reference is made to the side or 

 profile view (fig. 1). This 

 figure shows the head and 



part of the thorax of a Fig, 1. 



young larva. The tho- 

 racic rings bear rows of 

 bristles, so that the be- 

 ginning of the thorax is 

 readily made out. In 

 the illustration the head 

 is not fully extended; 



therefore the 



two 



eyes, 

 collections of dark- 

 coloured granules just in 

 front of the brain, appear 

 as if situated in the first 

 segment of the thorax. 

 The downward-pointing 



nozzle is seen in front. Head and Prothorax of young Cecidomyia 

 and on the forehead above Larva (profile). 



it two finger - shaped Above a single rust-spore proportionately 

 leelers or antennge. i he enlaro-ed. 



jaw - muscles, situated 

 inside the forehead 



just behind the antenna?, are attached to the mouth-parts 

 below and to the wall of the head above. The most con- 

 spicuous feature of the head, however, is a pair of dark- 

 coloured three-pronged pieces of horn (of which only the 

 nearer one is shown in the large profile view), so arranged as 

 to form a supporting framework for the attachment of muscles, 

 one prong extending forwards to near the mouth-parts, 

 another extending backward and thinning out in the region of 



