402 MR. TUFFEN WEST ON THE FOOT OF THE FLY. 



but soon again flew back to tbe window, where it had precisely the same difficulty in 

 pulling its imlvilli from the glass as before ; but after observing it some time, and at last 

 trying to catch it, that I might examine its feet with a lens, it seemed by a vigorous effort 

 to regain its power, and ran quite actively on the glass, and then flying away I lost sight 

 of it." This observation it is not easy to explain, at first sight. Kirby thought "one 

 Blight conjectm-e that from some cause (perhaps of disease) the hairs of i]xQ pulvilli had 

 poured out a greater quantity of this viscid material than usual, and more than the 

 muscular strength of the fly was able to cope with*. 



Revolving the subject in my mind, I have come to the belief that the fly in question was 

 struggling against its impending death from "Empusa"; some facts I have observed tend 

 to confirm the idea, but time has not allowed of my working it out. 



The great knowledge of the habits of insects possessed by the author whose labours we 

 are now considering, and of the remarkable adaptive modifications of different structures to 

 their varying economy, enabled him to feel the necessity of always studying these in thek 

 mutual relations. 



He also recognized tJie importance, for the purposes of a Natural Classification, of a 

 thorough knowledge of the feet in insects ; and especially in the Coleoptera. His obser- 

 vations on this head have been so thoroughly incorporated by Mr. Westwoodt (1839-10), 

 who has largely added to them, that the student will best consult the former through the 

 last-named author. It does not consist witb my present purpose to quote these observa- 

 tions, which are rather for the entomologist ; but the value of the remarks on the feet in 

 the different orders and genera, where they appear each under its proper head, is very 

 great, and a valuable clue is thus furnished to one desirous of a guide to these parts in this 

 numerically immense section of Animal Life. Mr. Westwood's work is not a micro- 

 scopical one ; yet the entomological descriptions of the feet given in it are so apt and 

 expressive, that I shall avail myself frequently of them in the course of the following 

 pages. 



The possession of a special apparatus by insects having climbing habits is mentioned 

 as having been already skilfully pointed out ; and a remark also occurs of interest from 

 its showing a recognition of the similarity between the feet of the Diptera and of some of 

 the Coleoptera : — 



" They [the Brachinides] are also characterized in many instances by having the tarsi 

 dilated, and the penultimate joint more or less bilobed in both sexes, a peculiarity 



resulting, as Bonelli has observed from the situations in which they reside, this 



structure being in fact analogous to the cushioned feet of flies as well as of those of the 

 true herbivorous beetles." 



I shall show how completely microscopic examination confirms the justice of this 

 analogy, by the minute details of the respective structures. 



In Dr. Burnett's Translation of Siebold and Stannius's ' Comparative Anatomy ' (185 i), 

 there appears in a foot-note a brief sketch of what the authors of this work considered the 

 then state of knowledge on this subject. 



" Many of the Curculionidse can grapple objects by means of the immoveable hooks on 



* Introduction, 7th edit., p. 451. f Introductlou to the Modern Classification of Insects. 



