BRODIE — PURBECK INSECT BEDS. 481 



middle Purbecks in Wiltshire, although the Cyprides and shells in 

 the former are quite distinct from those in the latter. The Insects 

 in the middle division especially bear a near resemblance to those in 

 the Vale of Wardour, and consist chiefly of wings and elytra. These 

 are from the " Pecten beds," Nos. 31 e^ seq. Many of them indeed 

 are identical, some few agreeing with species in the lower beds, and 

 some (apparently) with those of the Lias, and a few may be new. 

 The elytra and wings are generally detached, rarely collected together 

 in masses, lying in difFerent portions of the stone, and not in par- 

 ticular layers. They are, however, remarkable for their beautiful 

 state of preservation, the elytra usually retaining their elytrine or 

 chitine, and the wings their most delicate nervures and colouring. 

 In this they present a contrast to the insect relics in the inferior 

 strata. They are occasionally mingled with Corbula, Cyclas, and 

 Cypris. The wing-covers of beetles are tolerably abundant, but of 

 small size. I have observed only one perfect Beetle, a few minute 

 but peculiar larvae, abdomens, and only one entire dipterous (pro- 

 bably) insect. The detached wings consist chiefly of Gryllus, Acheta, 

 Blatta, and Libellula, most of which seem to be identical with spe- 

 cimens figured from the Vale of Wardour (see " Fossil Insects," 

 plates 2, 3, 4, 5, 6). One very beautiful wing resembles the Ephe- 

 mera of the Lias {ibid. pi. 10. fig. 14). In the lower beds (from 

 Nos. 94 to 128 in Mr. Austen's Section, some of which he denomi- 

 nates "Insect beds," and which form the top of the lower Purbecks, 

 see note, p. 478), elytra are very abundant, grouped together in 

 clusters, especially in one particular stratum at Durdlestone Bay and at 

 Ridgway near Dorchester. As many as sixty or seventy elytra and 

 several wings and bodies have been counted on one small slab. The 

 elytra generally retain their delicate sculptured markings, and some- 

 times the colour. They are mostly small, though a few larger spe- 

 cimens have been met with ; some are of great size, much larger 

 than any I ever procured in the Vale of Wardour, and rather more 

 so than the largest elytra from the Stonesfield slate. A few attached 

 elytra occur, but perfect beetles are extremely rare, only three or 

 four having been noticed. At Ridgway a very peculiar pupa is 

 rather characteristic, and a small beetle, allied to Notonectis, which 

 is an aquatic species ; and this possibly may account for its being 

 found entire, while all the terrestrial ones are disjointed and imper- 

 fect. The grouping together in masses is one distinctive feature in 

 the insect remains from the lower Purbecks in Dorsetshire ; the 

 wings too are usually broken, and portions of Insects are scattered 

 about in all directions, and the whole a})pear to have been carried 

 down a stream of some violence, and deposited at a considerable 

 distance from their original habitats. At any rate they nmst have 

 been exposed to some very destructive agency before they were im- 

 bedded in the mud of the waters in which they floated. In this 

 respect they differ from those in the Vale of Wardour, and in the 

 Lias generall)^ The smaller number of entire insects (scarcely any in 

 fact) is to be noted. 



At Ridgway the masses of elvtra have one uniform direction ; as 



