﻿Iviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Brodie in his valuable ' History of British Insects' informs us, that in 

 the marl-stones and shales of this age, in Gloucestershire and other 

 parts of the West of England, there are numerous remains both of 

 insects and plants occasionally mingled with marine shells, sometimes 

 also with freshwater mollusca of the genera Cyclas and Unio. One 

 shale containing Cypris is charged with the wing-cases of Coleoptera, 

 and some nearly entire beetles of which the eyes are preserved. The 

 nervures of the wings of the neuropterous insects are also found in a 

 very perfect state in the same bed. Throughout an extensive district 

 several bands of this lias have been termed insect-limestone, in con- 

 sequence of the great number of such fossils, no less than 300 speci- 

 mens of hexapods having been obtained, comprising both wood-eating 

 and herb-devouring beetles of the Linneean genera Carabus, Elater, 

 and others, besides Grasshoppers (Gryllus) and detached wings of 

 Dragon-flies and May-flies, or insects referable to the Linnsean 

 genera Libellula, Ephemera, Hemerobius, and Panorpa, the whole 

 assemblage belonging to no less than twenty-four families. These 

 have evidently been washed down into the sea by a river, which also 

 brought down the leaves of ferns and monocotyledons, together with 

 fragments of other plants, possibly dicotyledonous*. That no shells 

 of snails or any air-breathing testacea have been yet obtained must 

 be a mere accident, and we may consider ourselves in this and many 

 other districts as treading on the threshold of discoveries, which may 

 soon make us better acquainted with the contemporaneous flora and 

 fauna of the dry land. 



Until the year 1846, when Dr. Dunker described the Wealden beds 

 of the North of Germany, no well-determined specimen of the genus 

 Planorbis had been detected in beds older than the eocene ; and the 

 first species of Lymneus, more ancient than those of tertiary date, 

 was found by the same geologist. In the four years which have 

 since elapsed, Prof. E. Forbes has not only met with various species 

 of these genera in each of the three divisions of the Purbeck in Dor- 

 setshire, but has also obtained from the same rocks Valvata, Physa, 

 and Melania in abundance, together with the fruit of Chara, pre- 

 viously supposed to be characteristic of strata newer than the upper- 

 most chalk. You will find that some able palaeontologists have been 

 disposed to lean on the absence of pulmoniferous mollusca in all strata 

 antecedent to the eocene, in support of the theory of successive 

 * Prof. Buckman, Quart. Journ. Geol. Soc. vol. vi. p. 417. 



