of Buprestidse and ElateriJse. 177 



the whole head to be merely a firm framework for the mouth. 

 The correctness of this view is generally assumed. Chapuis and 

 Candeze concur in it entirely, and even try to support it by an 

 additional argument, which I cannot but think is of very doubt- 

 ful value — namely, that the head must have soft integuments 

 for the purpose of being retracted into the prothorax*. On the 

 subject of Goureau's theory f, according to which the whole of 

 the prothorax becomes head, Lacordaire observes that it does 

 not deserve refutation, that moreover it has been sufficiently 

 refuted by Leon Dufour and Pcrris; he considers Erichson's 

 interpretation so decidedly true that he looks upon that of 

 Ratzeburg and Low as an almost inexplicable error (Genera des 

 Coleopt. iv. 7. 1). 



Nevertheless Erichson's theory oiFers, as we have seen, insu- 

 perable difficulties in a physiological point of view ; and it seems 

 to be quite worth our while to try whether the matter may not 

 be differently regarded. Let us, then, first of all try to realize 

 fully the conditions under which the larvae have to exist in the 

 interior of the timber, and compare the structure of other larvae 

 burrowing in wood, particularly the apod larvae of Cerambycidse; 

 we shall then soon arrive at two important conclusions. Li the 

 first place, the mandibles must possess exti'emely powerful 

 flexors, which consequently must be too large to find room in 

 the proportionally small part which has hitherto been looked 

 upon as forming the whole head in the larvae of Lamiae and 

 Buprestidae; in the second place, the great demands upon the 

 power and endurance of these apod larvae cannot be satisfied by 

 the strength of the mandibular nmscles alone, however great ; 

 but power and accuracy in the guidance of the head — that 

 is, in the application and pressing of the mouth against the 

 timber during the act of burrowing — is required in no less de- 

 gree. In these sentences lies the key of the whole complicated 

 arrangement. A careful dissection will show, what is sufficiently 

 surprising, that no one has hitherto had an accurate idea of the 

 real extent, shape, and position of the head in the larva of 

 either Lamiae or Buprestidae. The fact is, that the protruding 

 anterior part of the head is uninterruptedly continued back- 

 wards into a very large skull, which, in the larvae of Bupres- 

 tidae, is so large that it actually reaches the very bottom of the 

 prothorax, so that the neck is on a line with the first pair of 



* " En efFet, dans ces larves la |)laque sous-cephalique, oornee k sa partie 

 aiiterieure, est devenue tres-moUe dans le reste de son etendue, parce 

 qu'ellfi doit se replier sur elle meme pom- rentrer avec les parties de la 

 bouche dans la gaine que lui forme le prothorax." (Chapuis et Candeze, 

 Catal. des Larves de Coleopt. pp. 131, 132.) 



t Ann. de la Soc. Ent. de Fr. ser. 2. vol. i. p. 26. 



Arm. ^ Mag. N. Nisi. Ser. 3. Vol. xviii. 13 



