468 Notices of Memoirs — R. B. Newton on Chonetes. 



with the metamorphism of these ancient masses and the consequent 

 genesis of the granites in their present form during the later stages, 

 or at the close of the Carboniferous epoch. The intrusion of granitoid 

 rocks perhaps accompanied, certainly succeeded, the solidification of 

 the granites, and continued at intervals down to the Permian quartz 

 porphyries. These rocks, called Elvan dykes, approximate, with 

 some few exceptions (notably the north and south Elvan of Water- 

 gate Bay), to the general strike produced by the north and south 

 movements, and in some cases, as near Camelford, to the main strike 

 deflections produced by the resistance of granite masses to these 

 movements, but in proceeding from granite to killas they ignore the 

 slight uptilt of the latter on the margin of the granites. 



The evidences in favour of the subterranean connection of the 

 Devon and Cornish granites are too strong to be ignored, and this 

 connection annihilates the application of the laccolitic hypothesis 

 advanced by me to account for the relations of the Dartmoor granite, 

 and at the same time contradicts the suggestion of the upheaval of 

 the granites in or through their surroundings. 



V. — On the Occurrence of Chonetes Pratti, Davidson, in the 

 Carboniferous Eocks of Western Australia. By R. Bullen 

 Newton, F.O.S., British Museum (Natural History). 



IN this communication the author directed attention to some valves 

 of a Chonetes recently discovered by Mr. Harry Page Woodward, 

 r.G.S., in rocks of Carboniferous age situated in the Irwin Eiver 

 District of Western Australia, which he referred to C. Pratti, a 

 species described and figured by the late Dr. Thomas Davidson in 

 the "Geologist" for 1859, Plate IV, Figs. 9-12, p. 116. As the 

 original description, contained only in the explanation of the plates, 

 is necessarily somewhat brief and imperfect, the following additional 

 characters were submitted : — 



(I) That the external surface of both valves, besides being 

 ornamented with very fine radiating striae, possess subimbricatiug 

 concentric lines of growth ; (2) that the extent of the cardinal 

 uiargia represents the minimum width of the shell ; (3) that the 

 granular asperites on the interiors of the valves are disposed in lines 

 as they reach the margins, having more or less an elongate appear- 

 ance resembling short tubular spines ; (4) that the external surface 

 of the ventral valve exhibits a number of small orifices placed at 

 irregular distances, which are probably basal attachments of spines, 

 a character known to exist in CJionetes papilionacea, C. Hardrensis, 

 etc. The author then gave the dimensions of the Davidson type 

 valves, together with those of the Western Australian specimens, 

 the latter being somewhat larger. A minute examination of the 

 Western Australian specimens and their comparison with the 

 originals of C. Pratti in the Davidson collection at the British 

 Museum has demonstrated the fact that they are mineralogically as 

 well as structurally the same brachiopod. This fact is of consider- 

 able importance, as the Davidson specimens at the time of descrip- 



