204 MINERALS AND GEOLOGY 



obscure and fragmentary examples of a supposed Protozoan, belong- 

 ing or related to the Forminifera, have been discovered in Canada 

 and at several European sites. A special genus has been framed for 

 their reception under the name of Eozoon* ; and the crystalline 

 strata in which they occur, and which were formerly classed as 

 formations of the Azoic age, are now generally known as " Archaean 

 strata." 



(6) Viewed broadly, the rock-representatives of the earlier portion 

 of the Palaeozoic age comprising ordinary slates, sandstones, lime- 

 stones, &c.^are characterized, more especially, by the presence of 

 graptolites, cystideans, and trilobites, associated with tabulated corals, 

 a great abundance of brachiopods (including species of the still 

 surviving genus lingula), and many examples of orthoceras an 

 extinct cephalopod with straight shell, and simple, unlobed septa. 

 These earlier Palaeozoic formations are also distinguished, negatively, 

 by the general absence or extreme rarity of land plants and verte- 

 brated animal remains. The middle and higher portions of the 

 Palaeozoic series including the Upper Devonian, Carboniferous, and 

 Permian formations contain, on the other hand, the remains of an 

 abundant terrestrial vegetation, especially characterized by the pres- 

 ence of ferns and large equiseta (catamites), accompanied by peculiar 

 types (lepidodendra, sigillarice, &c.), some of which apparently 

 indicate extinct transition groups between the higher acrogens and 

 the gymnosperms of existing nature. In these higher Palaeozoic 

 strata also, the remains of cuirassed and other ganoid fishes, all of 

 heterocercal type, occur more or less commonly ; together with 

 numerous tabulated corals, crinoids, brachiopods, and cephalopods, 

 related generally to earlier or lower forms whilst graptolites and 

 cystideans are no longer met with, and trilobites die out at the base 



* Examples of the Eozoon Canadense were first discovered in the Laurentian strata of 

 Ontario by the late DR. WILSON, of Perth, and others were subsequently found in the crystal- 

 line limestone of Grand Calumet Island on the Upper Ottawa, by the officers of the Canadian 

 Survey. Although their organic origin was strongly suspected at the time by SIR WILLIAM 

 LOGAN, it was not definitely admitted until the publication of DR. DAWSON'S microscopic 

 researches, followed by those of DR. CARPENTER in England. By many observers, however, 

 the organic nature of these remains is still contested, and it cannot certainly be regarded as 

 fully proved. One point, and a great point, in its favour, is the undoubted resemblance of 

 the better preserved Eozoon structures to examples of Palaeozoic Stromatopora. On the other 

 hand, it is somewhat remarkable that no other form of undoubted organic structure should as 

 yet have been discovered in these Laurentian strata or in the less crystalline limestones of. 

 the succeeding Huronian series. 



