Dr. H. Woodward — On Fossil Shells from Sumatra. 535 



the same age, and have all had a common origin, their remarkable 

 uniformity in mineral character and in physical structure, in dis- 

 tricts so widely separated as Cheshire and Nottingham, satisfactorily 

 demonstrates. The easterly attenuation of these beds indicates that 

 their source lay in an opposite direction, whilst the nature of their 

 materials — the angular grains of quartz, the abundance of mica, and 

 the abundance and often undecomposed state of the felspar in the 

 sandstones, point to their derivation from the breaking up of crystal- 

 line rocks such as granite and highly altered schists. These 

 sediments appear to have been drifted by westerly currents along 

 a strait or series of shallow channels, that in early Keuper times 

 stretched across the Midlands, and which, owing to preponderating 

 subsidence in that direction, covered a large area in the west, but 

 became narrower towards the east. This channel was shut in by 

 the southern flanks of the Pennine Hills on the north, and by the 

 Carboniferous rocks that flank the Leicestershire Coal-field and 

 Charnwood Forest on the south. For, north of a line drawn through 

 Alton, Derby, and Nottingham, the Basement Beds rapidly thin out, 

 while east of Burton-on-Trent they likewise speedily attenuate, and 

 eventually disappear ; nor have we any reason for supposing that 

 they were ever deposited any distance north or south of where we 

 now find them. 



IV. — Further Notes on a Collection op Fossil Shells, etc., 



from Sumatra (obtained by M. Verbeek, Director of the 



Geological Survey of the West Coast, Sumatra). Part IV. 1 



By Henby Woodward, LL.D., F.R.S., etc. ; 



of the British Museum. 



(PLATES XIV. and XV.) 



50. Triton, sp. (cast of). PI. XIV. Fig. 1. 



This cast indicates a fusiform turrited shell adorned by discon- 

 tinuous varices ; the spire is wanting ; it also shows that the shell 

 was transversely ribbed and corrugated ; the outer lip was strongly 

 plicato-dentate internally ; the aperture rather small ; canal mode- 

 rately long. 



From the general aspect of this cast, I think it probably may be 

 referred to the Triton corrugatum, Lamk., so widely distributed in 

 our European Miocene deposits ; and found living in Vigo Bay 

 (S. P. Woodward) and in the Mediterranean. 



Formation : — In light-coloured (Miocene) Tertiary clay-marl. 



Locality : — Government of the West Coast of Sumatra. 



51. Pleurotoma terebra, Basterot, 1825. PI. XIV. Fig. 2a, b. 

 Tleurotoma terebra, Basterot, 1825, Mem. geologique sur les Env. de Bordeaux. 



Paris, 1825, pi. 3. fig. 20. 



multinoda, Des Moulins, 1843, Revision des Pleurotomes ; Actes Soc. 



Linn, de Bordeaux, tome xii. p. 167. 



Dufourii, Des Moulins, op. eit. p. 180. 



■ (Clavatula) sinensis, Hinds, 1843, Proc. Zool. Soc. p. 38, pi. v. fig. 10, 



and 1844, Zool. Voyage of H.M.S. Sulphur, vol. ii. p. 17, pi. v. 

 fig. 11. 



1 Continued from the November Number, p. 500. 



