392 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 10, 



inundations or the rapid rising of rivers are sure to bring with them 

 the most abundant entomological harvest, insects being floated down 

 such currents in vast numbers, and congregated together in masses 

 on the banks, as thick as bees in a hive, or ants in an ant-hill. 



The circumstance also that such vast numbers of elytra have 

 been preserved, whilst the equally hard thorax, head, antennae, and 

 legs have entirely disappeared, is worthy of remark. I must admit 

 that I can offer no solution of so cuiious a fact, especially as the 

 wings, notvdthstanding their great delicacy, have left their impress 

 on the stone as clearly as any of the harder elytra. We here, how- 

 ever, see another instance in which nature had from the earliest time 

 adopted processes which we look upon when first applied in art or 

 manufactures as wonderful novelties. We see, in fact, that the modem 

 discovery of " natural printing," as it has been termed, whereby the 

 most delicate objects leave their mark upon the hardest materials, when 

 in contact under heavy pressure, has been anticipated in these fossil 

 imprints of wings of some of the smallest and most delicate insects. 



It has been suggested that the discovery of quantities of detached 

 elytra in a small slab might possibly be accounted for on the suppo- 

 sition that the insects to which they had belonged had been devoured 

 by some bird or other insectivorous animal, and had passed through 

 the stomach undissolved, owing to the presence of an asserted che- 

 mical substance in the elytra, which has been termed "elytriue." 

 I believe, however, that the term in question does not imply a distinct 

 substance in the elytra of beetles, but was given in consequence of 

 the experiments in which it was developed having been made upon 

 elytra. All the parts of the outer integument of a beetle have, in 

 fact, the same chemical composition, and consist of the substance 

 now known by the name of "chitine," which is analogous in com- 

 position to horn. Moreover entomologists are well aware of the fact 

 that other parts of a beetle are of as solid a nature as elytra ; they 

 know, for example, that one of the best beetle-traps is a toad, the 

 excrement of which generally contains entire specimens of some of 

 the rarest ground-beetles. 



With the exception, then, of the winged giant Ants, and of some 

 of the fragments of gigantic Dragon-flies' wings, there seems to be 

 such a general conformity with the Purbeck insects of Wilts *, that 

 I may almost reiterate the whole of my observations published in the 

 introductory part of Mr. Brodie's work. But, if the general con- 

 ditions of insect-life were so similar in the two districts, as indicated 

 by the remains in the Wilts and Dorset Purbeck formations, the mode 

 of destruction of such insect-Ufe must have been very different ; since 

 we found abundance of specimens of insects in a tolerably entire state 

 of preservation in the former, whUst in the latter scarcely anything 

 but fragments of wings or elytra, or a few segments of the abdomen, 

 occur. This indeed is the more remarkable, because, from the 

 tubular horny structure both of the leg-joints and antennae, it would 

 have been quite reasonable to have expected to have found them lying 

 detached amongst the masses of elytra, &c. of the beetles and other 

 insects to which they belonged. This dislocation and partial de- 



* The discovery of closely allied fossil Isopoda in both the localities is espe- 

 cially to be noticed. 



