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or tilestone forniiition, and was first brought to light by Wir R. Murchison. 

 Tliis was a ganoid fish of a type to wliich we find no living analogue ; internally 

 cartilaginous, it was defended externally by finely enamelled osseous plates and 

 scales, the skull and jaws being as naked and polished as its teeth. 



The Middle, or Cornstone, formation is characterised by the Cephalaspis, also 

 a cartilaginous fish, covered externally with strong plates of bone, having an 

 enormous crescent-shaped cephalic shield with a comparatively small body, jointed 

 so like the lobster that, when first discovered, it was supposed to be a Crustacean ; 

 its remains are found in the neighbourhood of Hereford associated with the spines 

 or rays of the dorsal fins of the Onchus, a placoid allied to the shark. 



The Holoptychius, a sauroid, or reptile fish, marks the Conglomerate or 

 Upper Division of the system. This creature must have been of great magnitude, 

 for its thick enamelled scales are as large as oyster shells, and its teeth rival those 

 of the crocodile. 



Although fossils are the safest guides to the identification of the sedimentary 

 rocks, still the geologist does not always find that synchronous formations yield 

 similar organisms. There is a striking dissimilarity in this respect between the 

 Old Red formations of Scotland and Devonshire. In the former, shells are entirely 

 absent, and the remains of fishes abundant ; while, in Devonshire, the converse 

 is the case. 



It would, therefore, have been impossible confidently to refer strata so 

 oppositely characterised to the same system, bad not Sir Roderick Murchison, 

 and M. de Verneuil, in their memorable researches in Russia, found there fishes 

 similar to those of Scotland and Herefordshire associated with the mollusca and 

 corals of Devonshire, proving incontestibly their co-existence, and that they con- 

 stituted together the fauna of one great Devonian ocean. Thus was confirmed the 

 accuracy of the classification previously adopted at the suggestion of Mr. Lonsdale, 

 founded on the assumption that the Devonshire fossils presented a character 

 intermediate between those of the Carboniferous and Silurian systems. 



Fishes of extinct genera were, until lately, the highest types of the animal 

 kingdom met with in the Devonian strata ; but Dr. Mantell, in the quarterly 

 journal of the Geological Society, has described a fossil reptile discovered last 

 year in the Old Red sandstone of Morayshire, which he has named the Telerpeton 

 Elgiuensis ; and also some fossil ova, supposed to be batraohian. These, with a 

 few footprints and .scattered traces of vegetation, resolved, in some instances, into 

 coal, appear to be the only indications of terrestrial life hitherto met with in this 

 system. 



At length, the era of the Old Red Sandstone passed away, and upon its upper- 

 most formation, the Conglomerate, were deposited the richly fossiliferous strata 

 of the Carboniferous Limestone, a purely marine deposit, averaging some hundred 

 feet in thickness, and containing the remains of fishes, shells, encrinites, and 

 corals. Overlying the limestone, we find a coarse quartzose sandstone passing 



