Dr. PiTTON on the Strata below the Chalk. 229 



[^Hastings Sand.'\ 



Cyclas media. Sand-clifF between Swanage and Punfield. In nodules of clay-iron- 

 ore, with Paludinae; also in hard subcalcareous grit. 



Paludina elongata. Same place and situation. 



Unio. One or more species occur in the concretions of grit within the sand-beds, be- 

 tween Punfield and the town of Swanage. 



Saurian Reptiles. Large bones of the Iguanodon have been found loose on the 

 shore at the foot of the sand-clifFs near Swanage, by the Rev. T. O. Bartlett ; 

 (see Dr. Buckland's Notice, already referred to*;) but their precise place in 

 the cliffs is still to be ascertained. 



Wood. Large portions of the stems of silicified coniferous trees have been found on 

 the shore under the sand-clifFs in Swanage Bay, by the Rev. T. O. Bartlett. 

 The stone into which they are converted is of a very dark brown colour, re- 

 ceives a fine polish, and does not effervesce with acids. 



[^Purbeck Strata.'\ 



Corbula alata. PI. XXI. f. 5. Numerous in slaty limestone, at Upway, on the north 

 of Weymouth, with Cyclas media. Durlstone Bay: Isle of Purbeck. 



Cycles media. PI. XXI. f. 10. This fossil occurs throughout the series of Pur- 

 beck strata, and is one of the most abundant fossils of the formation, some of 

 the beds being almost entirely composed of it. Upper beds of the series, at 

 Peverell Point, and Durlstone Bay, At Upway, west of the road, 50 feet above 

 the "Cap". 



C angulata. PI. XXI. f. 12. In " Quarry vein ", one of the strata worked for 



stone, near Swanage. In hard stone resembling the lower chalk, when indurated ; 

 Durlstone Bay. Of large size, in slaty stone, at Upway, N. of Weymouth. 



Cypris. Casts, in transparent carbonate of lime, of the interior of one or more small 

 species of this genus, occur in great abundance in the beds of slaty limestone, 

 which frequently includes rhombic crystals of carbonate of lime, at the bottom of 

 the strata above the "Dirt bed", as well as in the " Cap" over the Portland stone : 

 but it is difficult to determine the species, as the external surface is commonly 

 wanting. In a few instances an exterior spine or prominence, like that of Cypris 

 spinigera, PI. XXI. f. 3., is perceptible ; and in others the protuberance at the 

 end of the valves, represented in the figures of C. Valdensis, PI. XXI. f. 1., was 

 observed. It is not, however, improbable that some of the casts may belong- 

 to species different from both of these. Isle of Purbeck, and coast thence to 

 the west of Lulworth Cove. Quarries at Upway, north of Weymouth. Isle 

 of Portland : in the " slate ". 



Exogyra bulla. PI. XXII. f. 1, Durlstone Bay. 



Ostrea distorta. PI. XXII. f. 2. Durlstone Bay. The bed called " Cinder ", about 

 the middle of the strata which are worked for stone, consists almost entirely of 

 this and other species of oyster. 



* Proceedingsof Geol. Soc, vol.i. p.l59.; and Geol. Trans. Second Series, vol. iii. p. 421. et seq. 



