1868.] 



371 



[Packard. 



Fig. 6. 



The pupa 

 of Diplax, 

 in which the 

 eyes are 

 much larger, 

 and the legs 

 much short- 



in the rau'^h shorter legs and shorter abdomen, and the presence of 

 the deciduous tubercles.* (Fig. 7.) 



Individuals were seen which were supposed to have 

 imdergone their first moulting, being nearly as large again 

 as the freshly hatched larva and with the aladomen a little 

 longer. The assumption of the mature larva-form seems 

 to be in some respects a process of degradation. The 

 pupa is more decephaUzed than the recently hatched larva, 

 as the body is lengthened out backwards. In the changes 

 from the pupa to the imago, the insect seems to go 

 through a process of decephalization, or degradation, 

 observable in the greatly disjiroportioned head, and elon-' 

 gated, cylindrical, worm-like abdomen. This shows that 

 the Libellulidte, while the most typical of Neuroptera, 

 belong to a degraded form of the suborder, and stand 

 low down in the group. On the contrary, the most 

 the recently typical of the Hymenoptera, (the honey bee, for examT 

 hatched pie) and of the Lepidoptera, (c. r/ . , the butterfly) stand 



highest in their respective suborders. 

 ■ The larvffi after hitching were not observed through their transfor- 

 mations. It is probable that, like the young Ephemera, which, accord- 

 ing to Lubbock, moults 

 twenty times before as- 

 suming the imago or 

 winged state, the young 

 dragon-fly moults inore 

 than four or five times, 

 the usual number in the 

 insects with complete 

 metamorphoses. 



Considering the ocelli 

 as indicating two seg- 

 ments in the head 

 (these Proceedings, x., 

 pp. 28, 29), we have 



Fig. 7. 



seven segments forming the head, three the thorax, and eleven the 

 abdomen. The typical number, then, may be considered as amount- 



* Figure 7. Side view of the head of the larva of Diplax before the first moult. 

 c, deciduous tubercles terminating in a slender style ; their use is unknown ; 

 they have not been observed in the full-grown larva, e, the compound eyes. 1, 

 the three jointed antenna, the terminal joint nearly three times as long as the two 

 basal ones. 2, the mandibles, and also enlarged, showing the cutting-edge di- 

 vided into four teeth. 3. maxilhe divided into two lobes: d, the outer and an- 

 terior lobe, 2-jointed, the basal joint terminating in two seta?; andrt, the inner lobe 

 concealed from view, in its natural position, by the outer lobe, d. 4, the base 



