G. W. Tyrrell—Petrography of South Georgia. 435 
MemsBranipora FURINA, sp.nov. (Pl. XVIII, Fig. 7.) 
Zoarium unilaminate, adherent. age a 
Zoecia small, pyriporiform whenever they are not called upon to 
support an ocecium for a preceding zocecium; areas elliptical, average 
length -32mm., breadth ‘2mm.; many of the zocecia are closed by a 
slightly convex lid, in the centre of which, ina small depression, there 
is a tiny semicircular aperture surrounded by a faint rim; itis of course 
possible that these are not zocecia but avicularia, but I prefer to 
regard the lids as analogous to those of Lscharina(?) intricata, 
Lonsdale,’ especially as they occur freely in established lines of 
zocecia. 
Oecia abundant, ground-plan semicircular (no perfect specimen yet 
found). 
Avicularia very scarce, small sub-vicarious examples of the simple 
hour-glass type. 
This species is relatively abundant. 
EXPLANATION OF PLATE XVIII. 
(All figures x 12 diams. All figured specimens from Weybourne.) 
Fie. : 
1, 2. Membranipora fluonia, sp. nov. 
3,4. M. fonteia, sp. nov. 
M. cubitalis, sp. nov. 
| M. fulgora, sp. nov. 
M. furina, sp. nov. - 
(To be continued.) 
SE 
IJ.—Fourruer Notes on tHE PrerrocRapHy oF SourH Grorelia. 
By G. ‘ie TYRRELL, A.R.C.Sc., F.G.S., Lecturer in Geology, Glasgow 
University. 
f{\HE new material on which this paper is based has lately been 
received through Mr. D. Ferguson, who recently investigated 
the geology of the island, and collected the rocks described in an 
earlier paper.” It consists of twenty-seven rock specimens from the 
south-eastern end of the island, between Cape Disappointment and 
Cooper Island, and nine specimens from Gold Harbour on the north- 
east coast between Cooper Island and Royal Bay. All these were 
collected by the staff of the South Georgia Co., Ltd., under the 
instructions of Mr. Th. E. Salvesen, managing director, of Leith. 
Furthermore, by the kindness of Professor L. V. Pirsson, of the 
Sheffield Scientific School, Yale University, I have been enabled to 
examine a few beach pebbles collected from South Georgia in 1871 
by R. W. Chappell, a whaling captain. These consist mainly of slates 
and phyllites, with sheared, faulted, and quartz-veined greywackes, 
probably belonging to the Lower Division of the Cumberland Bay 
Series. ‘There is also a rounded pebble of a fresh vesicular lava of 
unusual composition which is described later in this paper. 
1 Dixon’s Geology of Sussex, p. 316, pl. xviii B, figs. 8, 8a, 8b. 
2 GEOL. Mac., Dec. VI, Vol. I, pp. 53-64, 1914; Trans. er Soc. Hdin- 
burgh, vol. 1, pt. iv, pp. 797- 836, 1915, 
