28 THE CLASSIFICATION OF INSECTS FROM EMBRYOLOGICAL DATA. 



nidiB, and other Aptera, and true Insects, we have thus, with the organization of 

 Insects proper, a repetition of the natural forms of the three classes of the type. 

 We have worm-like Insects, the Myriapoda, — Crustacea-like Insects, the Spiders, — 

 and true Insects, with wings, and six legs ; or, in another point of view, larva-like 

 Insects, Myriapoda, — pupa-like Insects, Spiders, — and true Insects, above all; the 

 larval and worm-like condition being both expressed in the form of Myriapoda, 

 while the pupa-like and Crustacea-like form is shown in the Spiders, and the true 

 Insects, as the highest stage of development, rank above all. So that the special 

 classification of Insects proper, again, sustains the general classification of Articu- 

 lata, in which we have ascribed the lowest rank to Worms, the intermediate position 

 to Crustacea, and the highest to Insects. 



EXPLANATION OF THE PLATE. 



Fig. 1. Egg of Eudamus Tityrus, natural size ; Fig. P, enlarged in profile ; Fig. I'', enlarged from 

 above ; Fig. 1°, a rib of the same egg still more enlarged. 



Figs. 2, 3, 4, 5, and 6. Larvae of Eudamus Tityrus, in different stages of growth. 



Fig. 7. Pupa of the same ; Fig. 7, the pupa in its loose cocoon, with the larva-skin cast at its side ; 

 Fig. 7% the pupa seen in profile ; Fig. 7'', the same seen from above. 



Figs. 8, 9, and 10. The larva before casting its last skin. 



Figs. 11, 12, and 13. The larva casting its last skin, and the pupa coming out ; seen in profile, Fig. 11, 

 from above, Fig. 12, and from below, Fig. 13. 



Figs. 14, 15, 16. The pupa entirely detached from the larva-skin, which hangs behind the abdomen ; 

 Fig. 14, seen in profile ; Fig. 15, from above ; Fig. 16, from below. The wings, legs, antennae, and 

 trophi are entirely free. 



Fig. 16'' represents the same pupa as Fig. 16, somewhat enlarged ; d d being the vesicular wings, 

 c c, the jaws, b b, the antennas, and a, the legs. 



Figs. 17, 18, and 19 represent the pupa entirely freed from the larva-skin, and somewhat more ad- 

 vanced than in Figs. 14, 15, and 16 ; the wings, antennae, and trophi being, however, still free. 



Fig. 19"^ represents the same pupa as Fig. 19, somewhat enlarged ; d d being the vesicular wings, 

 c c, the jaws, b b, the antennae, and a a a, the legs. 



Figs. 20, 21, and 22. The pupa nearly perfect ; the wings being flattened upon the sides of the body, 

 and beginning to adhere to the chest, as also to the antennas, trophi, and legs. Fig. 20, seen from the side ; 

 Fig. 21, from above ; Fig. 22, from below. 



Fig. 23. Eudamus Tityrus, in its perfect state of development. 



