842 I N S 



and the imago, in which it is furnished with full)' 

 developed wings : and being active like the larva 

 and provided with these organs, but so wrapt 

 up as to be easily enclosed within four short cases, 

 which arise in pairs from the back of the second and 

 third segments of the body. Here belong the 

 tribes of locusts, grasshoppers, mantes, cockroaches, 

 earwigs, bugs, and treehoppers, in all which the resem- 

 blance of the pupa to the imago ia very distinct. 

 Here, also, are generally arranged the dragon-flies, 

 and the may-flies (Ep/iemerte), but in these groups the 

 likeness of the pupa to the imago is less distinct, 

 the organs of respiration being quite different, as 

 above noticed, and the structure of the mouth being 

 totally dissimilar. These groups, accordingly, are 

 said by Mr. MacLeay to undergo a sub-semi-com- 

 plete metamorphosis. There is another peculiarity 

 connected with this species of metamorphosis, 

 which sufficiently proves that here we are inter- 

 mediate between the merely rudimental and the 

 perfect metamorphosis, and that the perfection of 

 the animal is not so dependent upon metamorphosis 

 as in the subsequent perfectly metamorphotic di- 

 vision. Thus there arc many species belonging to this 

 section, which remain throughout their life in a 

 state of imperfection ; of this, a common instance 



Figs. 44, Apterous imago ; 45, Winged imago of Velia rivulorum. 



occurs in the Hydrometridae, or water measurers. 

 These insects, which are to be observed skimming 

 along on the surface of the water, are generally 

 found destitute of the slightest rudiments of wings ; 

 they, however, continue their kind, but occasionally I 

 certain individuals will be found in company with 

 them with the wings fully developed. Now it is 

 impossible to regard the former as pupae, because 

 they have no rudiments of wings ; neither can we 

 consider them as larvae, because they are as large 

 as the winged individuals, and are able to pro- 

 pagate. Accordingly they have been generally 

 regarded as distinct apterous species ; but a more 

 extended investigation of these groups of insects 

 will prove the specific identity of these imperfectly 

 developed, but still perfect * ( as regards their 

 powers of propagation) individuals with the winged 

 specimens. Thus, there are many species, which, 

 instead of being generally wingless, are furnished 

 with short rudimental wings, and which are never- 

 theless capable of reproduction ; hence, as well as 

 from the structure of the rudimental wings, it is 

 evident that they cannot be pups, and yet it occa- 

 sionally happens that in a few individuals the wings 

 are fully developed ; thus the specific identity is 

 not questioned, why then should it be in the former? 



ie principle in either case being identical. 



3. In those species which undergo the perfect 

 norphosis of Latreille. the pupa is incapable 



ECT. 



of eating and walking, and may be considered as a 

 most characteristic state of the insect's existence. 

 Here belong the tribes of Coleoptera, Hymenoptera, 

 TMchoptera, and many Neuroptera and Diptera, 

 having an incomplete pupa ; the Lepidoptera having 

 an obtected pupa, and the remainder of the Diptera 

 and Strepsiptera having a coarctate pupa. We have 

 already noticed the distinction of these kinds of 

 pupae ; but as they all (including the coarctate pupae 

 when examined without reference to the external 

 covering formed of the indurated skin of the larva) 

 resolve themselves into one general mode of con- 

 struction, that of being inactive, and having the limbs 

 folded more or less closely upon the breast, it wil( 

 be convenient to examine them in one general view 

 Here, then, we find the form of the future insect 

 much more visibly impressed upon the insect than 

 during its previous state ; the head, thorax, abdom- 

 inal segments, and the various limbs, are more or less 

 discernible. The external covering in this state is 

 variable in its consistence, according to the situation 

 in which the pupa state is undergone ; thus in those 

 species especially belonging to the coleopterous, hy- 

 menopterous, and dipterous orders, which are safely 

 protected from external injuries, the pupae are sort 

 and the envelope membranous ; but in the Lepidoptera, 

 and more especially those which are naked, the pupa 

 (chrysalis) is of a hard texture. We have already, 

 in our article CHRYSALIS, given some general obser- 

 vations which are applicable to the construction of 

 this state, and which it will be unnecessary to repeat. 

 A clear idea of the arrangement of the limbs in the 

 three principal divisions of incomplete, obtected, and 

 coarctate pupa, will be obtained from the following 

 figures, in which the same letters refer to the same 

 organs throughout : fig. 46 representing a coleopterous, 



ww wpm 



Fig. 46. Pupa of the great water-beetle (Hydrous piceus). 



fig. 47 a lepidopterous, and fig. 48 a dipterous 

 pupa ; the latter stripped from the cocoon-like skin 

 of the larva. The letter H referring to the head, 



ii 



Fig. 47. Pupa of the tortoise-shell butterfly (Vanessa urticae). 



T the thorax, A the abdomen, a a the antennae, e e the 

 eyes, m the mouth, p the palpi, w the upper wings, 

 w w the posterior wings, 1 1 1 1 the legs. 



It must, however, be borne in mind, that in 

 these puptp the limbs have not yet acquired their 





