286 THE GEOLOGIST. 
FiSUES. 
Aucliciiaspis Salteri, Ej. G. J. 13. Plcctrodus iiiirabilis, Arj. S. S. GOG 
286. 704. 
Ccplialaspis Murcbisoni, E(j. G. J. 13. pustuliferus, Ag. S. S. G05. 
284. Pteraspis Banksii, IJiixley and Salter 
orn.atns, Ej. G. J. 13. 285. Gcol. Jour. 12. p. 100. 
Onohus iMurchisoni, Arj. S. S. GOT. 703. truncatus, id. G. J. 12. p. 100. 
tenuistriatus, Ag. S. S. GOT. 703. Spbagodus, Ag. S. S. GOG. 
(Shagreen of Onclius ? Thelodu.s 
Ag. fide Salter). 
Localities of Tilestones and associated Roch. — Kington, Ludford, near 
Ludlow, Bradnor Hill, Old Eadnor, Ilagley Park, Downton Castle, Tin 
Mill, 13rockliill and Hales End, near Malvern, Hole Farm, Abberley, 
Terton, near Stoko Edith, "Woolhope district, east of Llangadock. 
Lesmahago, Lanarkshire. 
(To he continued.) 
THE COMMON FOSSILS OF THE BRITISH ROCKS. 
By S. J. I^Iackie, Esq., F.G.S., F.S.A., &c., <fcc. 
CHAPTER III. 
The Remnants of the First Life ivorld and the Bottom RocJcs. 
(ConliniKd from page 241.) 
The divisional lino of the "Bottom Rocks" is not, however, to be 
placed at the point at M'hich life first appears. This groat series is 
naturally divided by differences of mineral conditions, by order of 
deposition, and in reality of ago, in our own country, and in other 
countries both of Europe and America, and apparently also, as far as 
our present information goes, in Asia and Africa. 
In Canada, below the equivalents of our Shropshire " Bottom Rocks" 
and of our lower Cambrian beds, as in the Highlands of Scotland, as wc 
have already obtained, are still more ancient beds of sedimentary origin, 
which have become crystalline. In Bohemia, in Finland, and in Scan- 
dinavia we have these primeval gncissic lands below the lowermost 
Silurian deposits ; but the geologists generally of other countries, except 
the Canadian, have not yet made much progress in this investigation, 
and it is only in very few instances that the distinctions between the 
older and younger gneiss have been noticed ; and so little regard as to 
geological ago has been ordinarily paid in the case of granitic rocks, 
that, knowing as we do the very various periods at which some of those 
