478 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



of hard blue limestone, somewhere about No. 31 in Mr. Austen's 

 list of strata*, towards the upper part of the middle series ; and it is 

 worthy of remark, that this layer, and the superior and inferior 

 beds connected with it, especially those designated " Pecten Beds," 

 hear a close lithological and zoological resemblance to the Isopod and 

 Insect limestones and associated strata at Dallards in the Vale of 

 Wardour, and their position accords pretty nearly with that of the 

 latter. Mr. Fisher has favoured me with the following Section of 

 the above in descending order, about 200 yards south of a small 

 stream, not far from the Preventive Station : — 



ft. in. 

 Two or three bands consisting of pinkish shelly limestone, ■n-ith Cor- 



bula, Ostrea, and Cyrena 1 6 



Clay 8 



Hard shelly limestone, yellow on the outside, with Ostrea and Bulla... 8 

 Clay, passing from dark blue at the top to yellow, with a little " beef " 



(fibrous carbonate of lime) 2 4 



Thin band of hard shelly stone, C(//;m, Car^fiwm, &c 2 



Hard marly limestone, breaking into rhomboidal fragments, with In- 

 sect remains 3 



Ditto, with lenticular masses of Corbula, and Insects 6 



Brown and blue clay, with shells and shelly rubble 2 



Marly shale 5 



Hard calcareous cream-coloured and blue marl, splitting into rhom- 

 boidal fragments ; lower part shaly, contains Insects 10 



Coarser and shelly stone, with Cypris 4 



Blue shaly clay 8 



Coarse shellystone 5 



Coarse shelly stone and blue clay. 



Total 10 9 



The strata containing Insects in these "Pecten beds" are some- 

 what slaty in their texture, varying in colour and hardness ; the blue 

 slaty limestone, which so closely resembles one of the Insect bands 

 in Wiltshire, passes into a yellowish-white fine-grained stone, the 

 prevailing colours being blue, white, and yellow ; it has a very uneven 

 fracture. Traces of minute plants occur throughout, consisting of 

 broken carbonized stems and rounded bodies which look like seed- 

 vessels. I requested my cousin Mr. W. R. Brothe, who resides at 

 Swanage, and is a most zealous and indefatigable collector, to examuie 

 the above more closely, and he informs me that he has since found 

 a number of \^'ings and elytra ; and he has been kind enough to give 

 me a small but interesting collection, from which j\Ir. Westwood has 

 made a selection for description and figuring. 



The inferior Insect-beds f, which consist of two or three distinct 



* Mr. Austen describes these as " blue and cream-coloured indurated marls ; " 

 they were probably deposited in brackish water. 



t In order that the Section may be quite clear to the general reader, I subjoin, 

 from Mr. Austen's ' Guide,' a copy of that portion of the Section which includes the 

 richest Insect beds, beginning with the highest of the lower Pnrbecks : — 



ft. in. 



94. Marly limestone, with thin band of shells 1 



95. Rubbly marlstone 2 



96. Cream-coloured marly limestone 2 



