134 Geological Society : — 



muddy mass, some of the debris of the houses having been carried 

 forward. The lower part of the flow was still in a state of motion, 

 and carried forwards balls of marly matter. 



It was difficult to approach the source of this flow on account of 

 the crevasses in the side of the mountain. An enormous breach 

 served as the orifice for the issue of the mud, which emitted, it was 

 said, a strong odour. The violent projection of this marly liquid 

 and " incandescent " (?) mass had carried away a considerable por- 

 tion of the flanks of the mountain, whose debris might be recognized 

 on the surface of the flow by the difference of colour. Great falls 

 were still taking place, throwing up a fine powder which rose into 

 the air like bands of smoke. There were also fissures and de- 

 pressions of the ground at other localities in the neighbourhood. 



3. " On a new Genus of Siliceous Sponges from the Lower Cal- 

 careous Grit of Yorkshire." By Dr. G. J. Hinde, E.G.S. 



December 4.— W. T. Blanford, LL.D., E.R.S., President, 

 in the Chair. 



The following communications were read : — 



1. " On the Remains of Small Sauropodous Dinosaurs from the 

 Wealden." By H. Lydekker, Esq., B.A., E.G.S. 



2. " On a peculiar horn-like Dinosaurian Bone from the Wealden." 

 By 11. Lydekker, Esq., B.A., E.G.S. 



3. "The Igneous Constituents of the Triassic Breccias and Con- 

 glomerates of South Devon." By II. N. Worth, Esq., E.G.S. 



During the investigation several hundred fragments were exa- 

 mined, the largest occurring at Teignmouth, between which place 

 and Dawlish the breccias are most varied in composition, and con- 

 tain the greatest proportion of granitoid rocks. The igneous 

 fragments were thus divided : — I. Granites ; II. Felsite group : «, non- 

 schorlaceous, b. schorlaceous ; III. Andesitic group ; IV. Miscella- 

 neous. Of these, including in all 76 varieties, I., II. b, and IV. 

 are plainly of Dartmoor origin in gross, the schorlaceous and con- 

 tact-altered rocks having belonged to the outer or to an upper zone ; 

 III. can for the most part be identified with the in-situ " felspathic 

 traps " of the neighbourhood. The non-schorlaceous division of II. 

 differs but little from Dartmoor elvans ; some may have been sur- 

 face-portions of felsitic dykes, or even fragments of felsitic lavas'. 

 The igneous fragments of the breccias, as a rule, are not much altered 

 structurally ; they are of local origin. 



The large blocks indicate the vicinity of high land abutting on a 

 shore-line. Of this high land Dartmoor is a relic. The transporting 

 power of water was perhaps supplemented by a glacial climate and 

 volcanic activity. De la Beche considered that igneous action 

 accompanied the earliest "red-rock" deposits. The "felspathic 

 traps " are known to be both antecedent to and contemporaneous 

 with the breccias, and there is evidence which points to their being 

 comprised within the period of igneous activity represented by the 

 Dartmoor elvans. The author says that there is a preponderance of 



