2 



THE GEOLOGIST. 



intermediate between the Fenestellicla and the GraptoHtes, and named 

 Didijonema {Grraptoi:)orct) socialis by Mr. Salter; also a small Ortlds 

 and a Scandinavian trilobite, Olenus alatus of Beck. The fossil 

 Dictyonemas 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 fi'om 

 these ancient silurian rocks — the Lingula-fiao'S. Let us cast our eyes 

 over the equivalent rocks in other lands. In ISTorth 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 Bennettii. 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 our planet. 



Whether the geographical distribution of particular species in 

 particular regions at that remote era will be established as a fact or 

 not, it is ceiiiain 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 \\ade, flat, mudd}' 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 theii' 

 unctuous passage the fine material particles finer and finer, leaving 

 tiny pools innumerable, shallow lagoons, and mimic lakes for 

 Hymenocarides and Trilobites to spoi*t and gi'ovel in. How glori- 



