232 Benj. D. Walsh on the Insects inhabiting the Gulls 



sel. He might as well draw three or four pictures of the gradually 

 progressive stages of development of the imago of a moth or a butter- 

 fly, after it has emerged from the pupal integument, the wings, &c. be- 

 ing gradually more and more developed in each successive stage, and 

 then dignify these stages with the high-sounding names of the succes- 

 sive stages of the semi-imago. In all those Orders where the pupa is 

 quiescent (Coleoptera, Neuroptera in the Erichsouian sense, Hymen- 

 optera, Lepidoptera and Diptera,) there are two grand and trenchant 

 distinctions between the larva and the pupa : 1st, that the former 

 has not yet moulted the larval integument and the latter has ; and 

 2nd, that — as has been well pointed out by Schauin {Ann. and Mai/. 

 Nat. Hist., London, 1863, p. 178, note,) — the former has the mouth 

 and anus externally open, and can consequently both eat and discharge 

 fzeces, and the latter has the mouth and anus externally closed by the 

 papal integument, and consequently can neither tat nor discharge 

 faeces* Now, although we cannot apply the second of these two cri- 

 teria to those Orders which have an active pupa, (Orthoptera, includ- 

 ing Pseudoneuroptera, Heteroptera and Homoptera,) because in these 

 the mouth and anus are never closed at all, yet here we may plainly 

 distinguish the pupa state by the homology of the moultings with those 

 of the Orders which have a quiescent pupa. For the pupa state here, 

 is evidently the period intermediate between the penultimate and the 

 ultimate moult, just as it is in the other case; the ultimate moult, how- 

 ever, here, as in the other case, involving the rejection of two integu- 

 ments, which are generally almost simultaneously rejected, but in Eph- 

 emeridte are rejected at a considerable interval of time. It is sinou- 

 lar that, in a Paper professing to treat of the development and morph- 

 ology of Hymenoptera, this grand fundamental distinction of Dr. 

 Schaum's and others, has not once been even alluded to by Dr. 

 Packard. 



* In some of these Orders there is, in addition, a third criterion— which, how- 

 ever, often admits of exceptions— namely, a difference in the legs of the larva 

 and pupa. For example, in Lepidoptera the larval legs when present, which 

 is not universally the case, are free; while the pupal legs are always present, 

 and are usually soldered to the body, except in the leaf-mining genus Microp- 

 teryx, where they are free. (Stainton's Entom. Annual, 1863, figs. 8 and 8*, Ac.) 

 On the other hand, in Coleoptera and Hymenoptera the larval legs when pre- 

 sent are free, and the pupal legs are always present and usually free, except in 

 certain Brachelytrous Coleoptera and Chalcidian Hymenoptera, where the pu- 

 pal legs are present, but the pupa is as much "obtected' - as that of any moth, 

 us I have myself observed and as was long ago stated by Westwood. "(IntroJ. 

 I, pp. 20 and ;',7 ; II, pp. 78— 0. J 



