2 
THE GEOLOGIST. 
intermediate between tlie FenestelHda and the Graptolitcs, and named 
Didtjonema {Grcqitoj'ora) soclalis by Mr. Salter; also a small Orthis 
and a Scandinavian trilobite, Olenus aJatus of Beck. The fossil 
Dictyonemse completely cover the surface of a black slaty layer at 
that place ; and near Maentwrog and Ffestiniog the same bed has 
been observed overlying the lighter coloured and more sandy mass 
of the Lingula-flags proper, and apparently forming a conformable 
bed of passage into the lowermost portion of the Llandeilo group. 
Such then, and so scanty, are all the trophies as yet obtained from 
these ancient silurian rocks — the Lingula-flagg. Let us cast our eyes 
over the equivalent rocks in other lands. In North America vast is 
the development of the Potsdam sandstones which represents them, 
but in these the fossils are like, and few. In Bohemia, Scandinavia, 
France, Georgia, and other places it is the same. 
From Newfoundland, during the past year, we have indeed been 
presented with a giant trilobite nine inches and a-half across, and 
named by Mr. Salter Paradoxides Bermettii. But this difference only 
of size from the other species of the same genus in these rocks, con- 
firms rather than depreciates the conclusion which Sir Roderick 
Murchison has come to of the paucity of life-forms at this early stage 
of the elaboration of the stratified crust of oui' planet. 
Wliether the geographical distribution of particular species in 
particular regions at that remote era will be established as a fact or 
not, it is certain that the range of organic forms was at its maximum 
then ; while the similarity of the forms presented in regions far 
remote and apart, seems certainly to indicate more equitable condi- 
tions of climatal relations. This is what we should expect from the 
general low oosy character of those tide-washed lands, and the still 
warm and reeking atmosphere in which the whole globe was pro- 
bably enveloped. 
Let us pause for one moment on the strange scene. That great 
expanse of sea, those wide, flat, muddy shores, over which the un- 
checked tides ran rippling with rapid speed in a thin sheet, waving 
into life the silken weeds, and ebbed as quickly, triturating in their 
unctuous passage the fine material particles finer and finer, leaving 
tiny pools innumerable, shallow lagoons, and mimic lakes for 
Hymenocarides and Trilobites to sport and grovel in. How glori- 
