Roberts—Pre-Cambrian Rocks. 13 
points, particularly in the arrangement of the ‘radial plates ;’ as, in 
that now under consideration the first two bifurcations of these plates 
form part of the ‘cup,’ which arrangement expands the arms so much, 
before they spring from the ‘cup,’ as to leave space for only a very 
narrow plate between them. 
The ‘pelvis’ or ‘base’ is hexagonal, tripartite, and very little larger 
than the attachment of the stem; aperture pentaphylloid ; the first 
‘primary radial’ is hexagonal, nearly half as wide again as long; the 
second ‘primary’ also hexagonal, about twice as wide as long; the 
third, or ‘scapula,’ as wide as the second, but cuneiform; and on 
each of its upper or bevel-faces there is another cuneiform or second 
‘radial plate,’ carrying on each of its bevel-faces the first arm-plate. 
There are four sets of three ‘interradial plates’ and four ‘anal plates,’ 
besides the narrow plates between the arms. The above plates are 
attached to each other, and form the ‘cup,’ from which spring twenty 
‘arms.’ ‘The ‘dome,’ or visceral portion above the arms, is very lofty 
in comparison with the ‘cup.’ The plates in the first row above the 
arms are much longer than wide, and give an appearance very dif- 
ferent from that of any other published species of this genus, found 
in the Mountain-limestone; above this row the plates are smaller, 
and of various shapes, except the summit-plates which are similar in 
their proportion and arrangement to those usual in Amphoracrinus,-— 
that is, one large plate at the summit surrounded by six other plates 
and the ‘proboscis.’ In the specimen here described the proboscis — 
is broken off, and the stem and arms are unknown. 
The height is 13 lines; depth of the ‘cup’ not quite 3 lines; dia- 
meter at the top of the ‘cup’ 12 lines long from the anal side to the 
anterior arms; transverse diameter or width 11 lines. 
‘From the peculiar form of this fossil I propose for it the 
name of Actinocrinus (Amphoracrinus) brevicalizx, 
IV. On tHe EXiIstence or Pre-CampBriAN LIFE-ERAS. 
By Gzorcz E. Rogrrts, F.G.S., Hon.Sec.A.S.L. 
es has been no lack, in the history of geological science, of 
suggestions as to how our knowledge may be advanced upon 
those obscure questions which yet ask for solution, both in the 
physical and palzontological departments of the study. Sometimes, 
by asurprising intellectual endeavour, we have been carried up to 
the moon, and asked to discover where its missing waters are, with- 
out which our useful satellite appears to be a sort of ‘house to let,’ 
—the idea having got into the mind which originated the enquiry, 
that the earth bad appropriated the said waters for the necessities of 
a supposed cataclysmal epoch. Also, we have been taken down, by 
speculative thinkers, at divers times, to depths beneath our terra- 
queous surface, and asked to pin some fundamental articles of 
faith upon schemes which show all existing there to be either fire, 
or water, or a zone of meteorite-mineral, or one of solid steel, or that, 
nothing existing there, the interior of our planet is a vacuum. It 
