4$^ Retrospective Criticism. 



E. S. (p. 148. fig. 30. a b) tends, I regret to say, from the additional initial 

 affixed to his signature, to show that there still remain some disciples of 

 that school, who, although they deem it an honourable mark of distinc- 

 tion to rank themselves as members of that society which bears the name, 

 and which ought also to adopt the principles, of the great Linnaeus, yet 

 apparently consider that the labours of that great master were, unlike those 

 of other men, susceptible of no further improvement ; and who consequently 

 overlook not only the labours of men almost equal in rank with himself, 

 but also the very principles which guided him throughout his bright career, 

 and which would doubtless have induced him to adopt, if not absolutely 

 to propose, those very alterations and improvements in science which his 

 would-be-considered disciples refuse to countenance and employ, if they do 

 not actually laugh at and deride, but which more accurate investigation 

 and by far greater numbers of the objects of such investigation have proved 

 to be well-founded and correct. I need not, in this place, attempt to show 

 the differences of structure which exist between the insects composing the 

 family called Crioceridae, to one of the genera of which, Donacia, the 

 subject of your correspondent's observations actually belongs; and the 

 family Leptiiridae, in the typical or chief genus of which, Leptura, your 

 correspondent has placed the insect alluded to, doubtless because Linnaeus 

 himself regarded those species with which he was acquainted as belonging 

 thereto. It is sufficient for my present purpose to point out the circum- 

 stance, that this difference in structure is borne out by difference in habits, 

 inasmuch as the true Lepturae do not form silken cells, but undergo a naked 

 transformation; whereas the Donaciae, as E. S. himself informs us, construct 

 cells for purposes which it may not be uninteresting to enquire, into, more 

 especially as E. S. has left the question, whether they are the production of 

 the larva or perfect insect, in doubt, and also in consequence of the circum- 

 stance described by E. S. involving the interesting enquiry of the hyberna- 

 tion of insects. 



Cases of the nature of those described by E. S. may be fabricated either 

 by the perfect insect or by the larva. If by the former, they may be con- 

 sidered as constructed either for the purpose of a general habitation, or 

 merely for the purpose of hybernation. But it appears to me very evident 

 that it was for neither of these purposes that these cases were formed. 

 Indeed, in respect to habitations formed by the perfect insect, for the pur- 

 poses of a general and constant, or even an occasional, habitation, Messrs. 

 Kirby and Spence {Introduction^ vol. i. p. 473.) remark, in treating upon this 

 subject, " From the next division of the habitations of insects — those 

 formed by solitary perfect insects for their own accommodation — I shall 

 select for description only two, both the work of spiders, which, indeed, 

 with the exception of the inartificial retreats made by the -^chetae, Cicin- 

 delae, and perhaps a few others, are the only ones properly belonging to it." 

 With regard also to the formation of habitations by the perfect insect for 

 the purpose of hybernation, the same authors (vol. ii. p. 440.) observe 

 that " it does not appear that any perfect insect has the faculty of fabri- 

 cating for itself a winter abode similar to those formed of silk, &c., by some 

 larvae. Schmid, indeed, has mentioned finding jffhagium mordax and 

 inquisitor F. in such abodes, constructed, as he thought, of the inner bark 

 of trees ; but these, as Uliger has suggested, were more probably the deserted 

 dwellings of lepidopterous larvae, of which the beetles in question had 

 taken possession." One of the circumstances mentioned by E. S. must 

 also be considered as sufficient in itself to prove that the perfect insect was 

 not the architect of the cases in question, since it cannot be supposed that 

 an insect living above the surface of the water, and constantly on the wing, 

 would select a spot for its abode under water. 



^ It only remains therefore tor regard these cases as the production of the 

 larvae: and here the researches of the same interesting authors will at 



