﻿Geological Society of London. 177 



and 0-77 per cent, of silica. The altered rocks contain an abund- 

 ance of quartz granules, due probably to the crystallization of pro- 

 gressiA'ely dissociated silica, as the specimens of rock in which these 

 granules occur do not contain a larger proportion of silica than those 

 in which its presence can hardly be detected under the microscope. 

 The proportion of alkalies in the different specimens does not 

 materially vary. 



Overlying the second quarry at the east end of the mountain is an 

 ash bed of reddish-brown colour, containing more than 10 per cent, 

 of protoxide of manganese and iiearly 20 per cent, of peroxide of 

 iron, and showing a great diminution in the per-centage of silica 

 when compared with the associated crystalline rock. 



The author further described the characters of the uralite-por- 

 phyry of the Mawddach valley near Dolgelly, which is of a greyish- 

 green colour, sjDotted with black, and consists of a granular base 

 inclosing patches and crystals of uralite, the outlines of which are 

 sometimes sharp and well defined, but generally rounded and merging 

 into the general base. 



2. " On new species of Belemnites and Salenia from the Middle 

 Tertiaries of South Australia." By Ealph Tate, Esq., F.Gr.S., Pro- 

 fessor of Natural Science in the University of Adelaide. 



The author noticed the occurrence in deposits of supposed Miocene 

 age in South Australia of a species of Belemnite (Belemnites senescens) 

 and a Salenia [S. tertiaria). These fossils were obtained from 

 Aldenga, twenty-six miles south of Adelaide, on the east coast of St. 

 Vincent's Gulf, where the long series of sea-cliffs contains an assem- 

 blage of fossils identical with that of the Murray Eiver beds. The 

 Salenia is especially interesting on account of the discovery of a 

 living species of the genus by the naturalists of the ' Challenger.' 



3. " On Mauisaurus Gardneri, Seeley, an Elasmosaurian from the 

 base of the Gault at Folkestone." By Harry Govier Seeley, Esq., 

 F.L.S., F.G.S., Professor of Geography at King's College, London. 



The author described the skeleton of a great long-necked Saurian 

 obtained by Mr. J. S. Gardner from the Gault of the cliff at Folke- 

 stone. The remains obtained included a tooth, a long series of 

 vertebrse, some ribs, bones of the pectoral arch, the femur, and some 

 phalanges, indicating a very large species, which the author referred, 

 with some doubt, to the genus Mauisaurus of Dr. Hector, founded 

 upon a Saurian from the Cretace.ms formation of New Zealand. He 

 gave it the name of Mauisaurus Gardneri, in honour of its discoverer. 

 A small heap of pebbles was found in the neighbourhood of the ribs, 

 and it was supposed that these had been contained in the stomach of 

 the animal.^ 



1 Mr. J. W. Hiilke, with regard to the pebbles, suggested that the animal may not 

 have swallowed them as an aid to the comminution of food in its stomach, but that 

 they were introduced in the stomachs of fish which it had swallowed. The flesh and, 

 subsequently, the bones of these would be digested and absorbed, whilst the indiges- 

 tible stones, if the stomach of the Plesiosanncs was like that of Crocodiles, would be 

 unable to pass through the small pyloric opening into the intestine, and must perma- 

 nently remain iu the stomach. 



DECADE II. — VOL. IV. — NO. IV. 12 



