an Essay on the British FormicidcB. 275 



particularly alluded to it in the former part of this Essay, in 

 the hope of inducing others to attempt the solution. It is most 

 probable that the ants imprison only the species of Staphylinidce, 

 and that all other beetles found there resort to the nests for the 

 purpose of feeding upon a suitable nutriment which they con- 

 tain, or for the purpose of undergoing their metamorphosis ; 

 many which are found in ants' nests during winter have un- 

 doubtedly sought that situation for the purpose of hybernation. 

 From the various species of Brachelytra I think there can be 

 little doubt the ants obtain an exudation similar in its nutri- 

 tive qualities to that which they obtain from the Aphides ; those 

 species which we see the ants carrying into their nests, tending 

 with such care, and which, on our disturbing their habitations, 

 they eagerly seize and carry off with the same precipitation as 

 their young brood, are undoubtedly conducive to an important 

 phase of their economy. Species of Coleoptera, such as Hetcerius 

 sesquicornis, various species of Llodes, Cryptophagus, Corlicaria, 

 Latridius and Droviius, all of which I have met with, cannot be 

 supposed to be in any way capable of furnishing nutriment for 

 the ants, but may still prove benefactors by feeding upon and 

 removing substances which might otherwise render their habita- 

 tions more or less foul and unhealthy. 



Of all the families which compose the insect-world, there is 

 none in my opinion, which presents such wonderful varieties — I 

 may say eccentricities of form, as the Formicidce ; the organs of 

 manducation in some species, as in Drepanognathus and Eciton, 

 present an elongation equalling the length of the insects them- 

 selves ; in Atla, and some other genera of that family, they are 

 thickened and expanded to such a size as to be nearly equal to 

 one half of the head itself; then again, as a reverse of this, in the 

 males of some species of Myrmecina, the mandibles are rudi- 

 mentary and in others obsolete. The antennae partake of every 

 variety of length and thickness, and the palpi of every number of 

 joints between six and one ; the variation in the number of the 

 joints of the antennae, forms perhaps one of the most remarkable 

 deviations from what may be considered the normal number, 

 namely, twelve in the female and worker of the social species, 

 and thirteen in the males of the entire group of this class of insects. 

 In the genus Cryptocerus and its allies, several remarkable deviations 

 from the usual number of joints in the antennae are met with: thus 

 in Orectognathus the number is six in the worker ants, whilst in 

 Cryptocerus they vary from nine to twelve in the workers. Re- 

 markable as these deviations certainly are, they are not in my 



