1844.] 499 



The effect of cavities, when once formed in the bed of a rapid 

 river or tide, is to occasion whirlpools, which set in rotation the 

 matters within the cavity, the heavier bodies remaining within it, 

 while the lighter are ejected. In this way, it appears to me that 

 pits in the chalk may have been kept open for some time after the 

 deposit of the crag had commenced. 



The bending down of the lower strata of the crag into the 

 hollows of the larger and deeper pipes, may be regarded as an 

 extreme case of the stratification conforming itself to pre-existing 

 irregularities of surface, a conformity which is so apparent in the 

 same strata when extending over the broad and shallow hollows in 

 the chalk. A subsidence to a limited extent in matters so de- 

 posited is not incompatible with the mode and circumstances of 

 their deposition. 



January 8, 1845. 



George Dawson, Esq. of Birmingham, was elected a Fellow of 

 this Society. 



The following communications were read : — 



1. On the Discovery of the Fossil Remains of ^TD^^iK'L and other 

 Reptiles in Sooth Africa. By Andrew Geddes Bain, 

 Esq., Surveyor of Military JRoads under the Coqjs of Royal 

 Engineers. 



The district in which these fossils were found is on the eastern 

 frontier of the Cape Colony in South Africa, about 500 miles 

 east of Cape Town. No granite has been observed here, and the 

 lowest rocks are stratified, and in consequence of the dip, though 

 variable, tending on the whole towards the interior of the country, 

 the lower members of them are those nearest the coast. 



A red quartzose crystalline sandstone is described by the author 

 as the fundamental rock, and as altei'nating with a talcose slate. 

 This sandstone is assumed to be of the carboniferous period, 

 vegetable impressions, apparently of a Lepidodendron, having 

 been found in it, and it is traced by the author towards the west, 

 parallel to the coast to within 50 miles of the Cape. 



Over this there occurs a rock, called by the author a claystone 

 porphyry, containing fragments of the sandstone ; next an ar- 

 gillaceous slate, alternating with sandstone and containing thin 

 laminae of limestone, and at a little distance is a stratum full 

 of vegetable remains. 



Further to the north is a ferruginous sandstone with argillo- 

 calcareous nodules, in which nodules were found the remains of 



