260 PREDACIOUS AND PARASITIC 



decreasing in size towards the tail, the last segments, however, 

 sometimes widening out slightly, so that the larva presents a slight 

 resemblance in shape to a fish. The head is proportioned to the 

 body, but small rather than large, and armed with a pair of formid- 

 able mandibles, as seen in PI. XIII., Fig. i. No good description 

 has been given of the mouth-organs, Reaumur's statement that the 

 mandibles are tubular being erroneous. The labial palpi are long, 

 porrected, and three jointed. The antennae are long, and present 

 the tapering appearance of a whip-lash. On examination with a 

 fairly high power, the scaly structure of the epidermis is readily 

 seen, as shown in PI. XIII., Fig. i, and the extremity, which 

 appears to consist of two delicate joints, terminates in a fine 

 bristle. 



The eye will quickly attract attention by its peculiar arrange- 

 ment of several ocelli, grouped in slight protrusions on either side 

 of the head, and giving not the slightest indication of the extraor- 

 dinary development which the corresponding organs assume in the 

 perfect insect. Situated distinctly behind the lenses may be seen 

 the mass of pigment cells, which, being dark, is obvious even 

 through the egg-shell before the larva is hatched. The peculiari- 

 ties of the eye can be' observed by reference to Fig. 8, PL XIII. 



The mandibles, which are deeply grooved on their inner sur- 

 faces to form channels within which the hollow maxillae play freely, 

 bear at each extremity a curious pad, which is depicted at Fig. 7 

 of the same plate, and which is surmounted by a stiff fine bristle, 

 the presence of which explains in some degree why an aphis, once 

 touched by the mandibles, rarely escapes. 



About ten days after oviposition, in favourable weather, the 

 eggs, which at first have a very delicate greenish hue, become 

 slightly opaque, and then darken, and in a few hours the marking 

 of the segments and the pigment of the eye become visible 

 through the thin shell, as shown at Fig. 2, PI. XII. A slight 

 observation shows that, unlike some other families, the head 

 remains in close proximity to the microphyle, the posterior end of 

 the embryo being turned up so that the entire shape is somewhat 

 that of a flattened C- ^i^ examination of the contents of the egg 

 at this stage reveals the fact that the embryo is developed around, 

 as it were, the yolk, which is embraced by the anterior and poste- 



