330 Viscount d'ARCHiAC anf? M. deVERNEUiL. 



IX. Insecta. — It has long been doubted if animals of this class could have lived 

 in the ancient periods ; and then, on the other hand, the extreme delicacy of their 

 parts, at least in the greater number of the orders, is such, that a hope could 

 scarcely be entertained that any traces of those which did exist should have been 

 transmitted to us : all doubt on this subject has however ceased, two species belong- 

 ing to the family of CurculionidcB having been found in the coal-fields of Coalbrook 

 Dale, as well as a Neuropterous insect, which closely resembles the genus Corydalis 

 now living in Carolina; also a Libellula, or an insect related to the PhasmidcB^. 

 As to the Orthoptera and Arachnides, mentioned in the general treatises on the 

 science, we have not yet sufficiently precise indications relative to them to reckon 

 upon here. Count Sternberg has likewise announced the discovery of a fossil scor- 

 pion in the coal-measures at Chomle, near Radnitz in Bohemiaf. It is further easily 

 conceivable, that, as insects could only leave traces of their existence in exceptional 

 and very rare instances, it is very improbable that we should ever have a satis- 

 factory knowledge of this part of the fauna of the ancient formations. 



X. Crustacea. — The Crustacea of these far-distant epochs belong almost exclusively 

 to the family of Trilohites, in which a great number of genera have been established. 

 What we have already said relative to the uncertainty of many of the approxima- 

 tions and determinations of genera and species of bivalve shells, is much more 

 strongly applicable to the Trilohites, of which, as it is rare to have at once under 

 our observation any great number of complete specimens of each species, we are 

 reduced to the necessity of taking some isolated and external characters to esta- 

 blish not only a species, but even a genus ; and we are only acquainted with the 

 organization of these animals by more or less distant analogies, so that these in- 

 complete characters being the result of the imperfect state of the casts, the uncer- 

 tainty which reigns throughout this branch of the science, notwithstanding the 

 special works of which it has been the subject both in Europe and in America, 

 may be conceived. 



The Trilohites begin to appear in the most ancient beds in which any organic 

 remains of the animal kingdom have yet been observed. They seem also to have 

 been peculiar to the Palaeozoic epoch, not even continuing so high as the upper 

 part of the Carboniferous system ; a circumstance which agrees with their rapid 

 decrease in proportion as they rise from the most ancient Silurian beds towards 

 the succeeding deposits, as pointed out by Mr. Murchison J. 



The Calymene, which are very abundant in the Silurian system of Europe, are 



* Dr. Buckland's Bridgewater Treatise, vol. i. p. 409 ; vol. ii. p. 75. 



t See Verhandl. Gesel. Vaterl. Mus. in Bohmen, 1835; also Dr. Buckland's Bridgewater Treatise, 

 vol. 1. p. 406, and note, vol. ii. p. 74, PI. 46'. 1836. 

 X Silur. Syst., p. 647, 1839. 



