138 Geological Society, 



vial flat is terminated by sand-hills, beyond which occurs granite in- 

 tersected by numerous greenstone dykes, and then commence the 

 savannahs, which are traversed by large beds of conglomerate often 

 containing iron ore, and pierced with lofty porphyritic hills. The 

 savannahs are supposed to be the bed of an ancient lake. A region 

 in which much jasper occurs next succeeds, and then a remarkable 

 range of granitic mountains ; and the author directed especial atten- 

 tion to the insulated rocks of grotesque form abounding in the di- 

 strict. He also remarked on the probability of gold being found in 

 the river-courses, and on the appearance of the well-known diamond- 

 matrix of Brazil. 



A letter was next read from Mr. Trevelyan, remarking on the oc- 

 currence of polished and scratched surfaces in the neighbourhood of 

 Conway, on the ascent of Moel Siabod, from Capel Carig, on Snow- 

 don, and in other localities in North Wales. 



Dec. 18. — A paper was read " On the Pipes or Sandgalls in the 

 Chalk and Chalk-rubble of Norfolk." By Joshua Trimmer, Esq. 



The observations recorded in the present paper were made in chalk 

 pits near Norwich, and the surface of the chalk was observed to be 

 furrowed by irregular cavities, or deep cylindrical conical pipes, en- 

 tering the chalk from the channeled surface. The contents of the 

 furrows appeared to be fine sand mixed with a light- coloured amber 

 or yellow ochre, the former often filling up the cavities both here 

 and elsewhere. The author considers, that although chemical agency 

 may have assisted in the formation of these cavities and pipes, yet 

 that it is necessary to admit also mechanical action, and he refers to 

 several instances of the known efifects of rain-water on cHffs, and ex- 

 cavations of basins in river-beds, in proof of the probability of his 

 opinion being correct. 



Jan. 8, 1845. — The following communications were made : — 



A paper by Mr. A. G. Bain " On the Geology of the South-East- 

 ern extremity of Africa." 



The principal object of this paper was to describe the district in 

 which certain remarkable fossils had been obtained by the author and 

 forwarded to England. The lowest stratified rock in this district is 

 a red sandstone containing fragments of plants, which seem to re- 

 semble a common carboniferous species {Lepidodendron Sternbergi) . 

 Over this rock, and conformable to it, is a conglomerate of claystcne 

 porphyry containing pebbles, and to it succeeds clay slate. The next 

 is the fossiliferous rock, and it consists of a disintegrated sandstone 

 containing argillaceous matter in septarian nodules, the fossils being 

 found in the nodules. 



A notice, by Prof. Owen, of one of the genera of animals {Dicy- 

 nodon) whose remains were forwarded by Mr. Bain. The most im- 

 portant character in this genus is the possession of two large tusks 

 like those of the walrus, but the general structure of the bones indi- 

 cates distinctly the reptilian character of the animal. The first of 

 the species described by Prof. Owen was named D. lacerticeps, from 

 its analogies with the lizards. In this species there is an exhibition 

 of unusual strength in the bones of the face, but there is no mark of 



