396 PREDACIOUS AND PARASITIC 



greens of the Chrysopidcs^ the elegant reticulations of their ample 

 wings, and the metallic brilliancy of their protruberant eyes, place 

 them among the most beautiful of insects. 



It has been already mentioned that the larvae of these two 

 groups resemble one another very nearly in general characters, but 

 present also many points of difference. 



In the last section I described the more important appendages 

 of a larva of Chrysopa, which were delineated with some detail on 

 Plate XII. The tapering length of the organs and the specialisa- 

 tion of the parts seems to indicate that the development has 

 progressed considerably beyond that of the Heirierobiidce^ and one 

 might almost think that in the Chrysopidce the evolution of the 

 larva had reached its maximum, did we not know that in such 

 things there is no finality. The corresponding organs of the larva 

 of an Hemerobius, shown on PI. XVIII. at Figs, i, 2, 3, and 4, will 

 illustrate this difference very clearly. The chitinous external 

 casings are much more fully retained, forming upon the palpi a 

 close series of incomplete rings, or, rather, perhaps, of flat plates 

 tapering to the ends and bent into segments of a circle. These 

 rings or plates are of irregular length, and are regular in their 

 disposition only inasmuch as they are so arranged as to cover the 

 surface equally. In fact, their appearance at once gives rise to the 

 notion that the chitinous covering has originally been continuous, 

 or comparatively so, but that the necessity, and consequent efforts, 

 at flexion have first wrinkled and ultimately separated (on the lines 

 of the wrinkles) the hard surface into a series of irregular plates, 

 which, disposed upon a flexible membrane beneath, present no 

 obstacle to the free movement of the organ. The palpi are com- 

 paratively short and thick, while the first and second joints of the 

 organs which are equivalent to labial palpi are encased in a con- 

 tinuous chitinous coat. The maxillary palpi — which I have else- 

 where spoken of as antennae — exhibit in some of the larvae of 

 Hemerobius enlargements as shown in the drawing, which recall at 

 once the characters of the antennae in some of the less developed 

 (or retrograded) Aphidida. The impression thus formed, that the 

 larva of Hemerobius represents a less specialised development than 

 that of Chrysopa is confirmed when we observe the short and 

 slight nature of the terminal bristles. 



