350 eeport— 1879. 



tion is the absence of all evidence of volcanic action in their neighbourhood and 

 of debris, the result of abrasion. 



In the higher region petrified timber abounds, but no coal is found ; while in the 

 lower coal is abundant. The valley of the Tugela, which has been cut through the 

 sandstone and trap to more than 2,000 feet in many places, reveals a depth of 1 500 

 feet of sandstone in diminishing strata, and occasionally shows basaltic trap at 

 apparently long intervals of deposition. 



TUESDAY, AUGUST 26, 1879. 



The following Reports and Papers were read : — 



1. Fifth Eeport on the Underground Waters in the Permian, New Bed 

 Sandstone and Jurassic Formations. — See Reports, p. 155. 



2. Report on the Progress of the ' Geological Record: 



3. On the replacement of Siliceous Skeletons by Carbonate of Lime. 

 By W. J. Sollas, M.A., F.G.S. 



The author gave an account of certain calcareous fossil remains which exhibit, 

 both in gross and minute structure, a close resemblance to certain existing siliceous 

 sponges, and which differ widely from any known form of calcareous sponge. The 

 natural inference appeared to be that the calcareous fossils were once siliceous 

 sponges, the siliceous parts of which had undergone replacement by carbonate of 

 lime. The alternative view that the fossils were originally calcareous, and that they 

 represent an extinct group of Calcispongia, was discussed and shown to present far 

 greater difficulties to the zoologist than the inferred mineral replacement offered to 

 the chemist. Siliceous sponge spicules were stated to be remarkably soluble, 

 yielding readily to the attacks of minute boring algas, and undergoing solution in 

 sea water soon after the death of the sponge which possessed them. 



The Radiolaria of the Carboniferous limestone were likewise regarded as having 

 once possessed a siliceous composition, which they had since exchanged for a 

 calcareous one. 



4. On Carboniferous Polyzoa and Palceocorynm. By G. R. Vine. 



In this paper the author drew attention to the inadequate study that had been 

 given to the Carboniferous Polyzoa. During the last few years vast masses of 

 shales, containing polyzoal and other remains, have been brought to light, but none 

 that he was acquainted with excelled in richness the Hairmyres debris. Here the 

 specimens were well preserved, and the characters of the several species almost 

 perfect. 



The author considered that it was too early yet to draw up a classification that 

 would be satisfactory to all naturalists. Attempts had been made to do this, but 

 many details had to be furnished that could only be furnished after close study. 

 Besides the Fenestetta, other genera were alluded to in theraper, such as Ceriopora 

 Hhabdomeson, Hyphasinapora, Glauconome, and Diastopvra, but these are being 

 studied analytically, and further details of their structure will be brought forward 

 in a future report. 



