330 Reports and Proceedings — 



inliers, in the Triassic area of Bridgewater, are unlike the Quantock 

 rocks in character. The limestones of Asholt and Hollwell, asso- 

 ciated with slates of the Ilfracombe series, are very similar to varie- 

 ties of the South Devon limestone, and are quite unlike the lime- 

 stone of Cannington Park. 



3. " The Whin Sill of Teesdale as an Assimilator of the surround- 

 ing Beds." By C. T. Clough, Esq., F.G.S. 



Owing to the general absence of mechanical disturbance, the 

 author is of opinion that " the Whin consists in part of altered sedi- 

 mentary beds, that it partly represents beds which were once in the 

 position it now occupies, that it did not make room for itself simply 

 by thrusting aside these beds, but also by incorporating them into 

 itself." He proceeds to describe sections at Caldron Snout, Cronkley 

 Fell, Noon Hill, etc., which seem to him inexplicable on any other 

 theory. The author discusses objections on chemical grounds, hold- 

 ing that the general uniformity in chemical composition of the Whin 

 may be explained by supposing the absorbed beds to have permeated 

 a large mass of the Whin, as an alloy does melted metal. He thinks 

 the explanation may be extended to other intrusive masses. 



4. "On the Silurian Bocks of the Valley of the Clwyd." By 

 Prof. T. M'Kenny Hughes, M.A., F.G.S. 



The author gives a preliminary sketch of the Silurian rocks of the 

 southern and western part of the Clwyd valley. He describes first 

 some beds below the horizon of the Denbigh Grits at Ffriddfawr 

 which agree very well in their characters with the base of the 

 Coniston Grit, and others near agreeing with the passage-beds 

 between these Grits and Flags. He next describes sandstones in 

 the Cly wedog valley, the equivalents of the lower Grits ; and lastly, 

 at Bod Renail, flags, etc., the Pale Slates, which contain Graptolites, 

 and are thus to be identified with the Graptolitic mudstones of the 

 Lake-district. Thus he is of opinion there is a basement-series here 

 for the Silurian, corresponding in all its details with that in the 

 Lake-district. 



II.— May 28, 1879.— Henry Clifton Sorby, Esq., F.E.S., President, 

 in the Chair. — The following communications were read : — 



1. " On the Endothiodont Beptilia, with evidence of the species 

 Endothiodon uniseries, Owen." By Prof. R. Owen, C.B., F.R.S. 



The author referred to the characters assigned by him to his 

 Endothiodon bathystoma, which had the alveolar borders of both 

 jaws toothless, perhaps covered with horn during life, as in the 

 Chelonians ; whilst within this border there were three series of 

 teeth both in the palate and the mandible. He next described a new 

 species, under the name of Endothiodon uniseries, founded upon the 

 fore half of a skull, having only a single row of teeth in the palate, 

 a character which may prove to be of generic importance. The 

 author finally discussed the relationships of this genus, which he 

 regarded as belonging to the order Anomodontia, and as showing, 

 like Oudenodon, traces of derivation from Dicynodon in the presence 

 of caniniform pi-ocesses in the upper jaw. The development of teeth 

 interior to the alveolar margins in both jaws was to be regarded as a 



