82 Feather stonhaugh's Geological Report. 



the history of the ancient ocean, which harmonizes with every 

 other branch of organic existence. Of the four orders offish 

 established by him, the two first, placoidians and ganoidians, 

 exclusively occupy the groups below the chalk. It appears 

 that the vertebrated animals of the waters of that period be- 

 longed altogether to a class which constitutes a very small 

 portion of the existing ones. The fishes of this period, all of 

 which preceded the saurians, show an approximation to their 

 structure, as if nature was preparing for them. Those long 

 pointed substances called ichthyodorulites, which are also 

 found in the lowest parts of this group, Mr. Agassiz considers to 

 have belonged to a large shark-like fish. This ancient period, 

 therefore, instead of being almost devoid of life, appears to 

 have possessed the types of a great portion of the different 

 orders of marine animals now existing, the individuals of which 

 were all perfect in their structure for the ends they were 

 intended to accomplish, and had a sufficient analogy to what 

 exists at present, to warrant the opinion that they were amongst 

 the steps of a general plan of progression, accommodated 

 entirely to the then existing state of the surface of the planet, 

 and only preceding others, which further changes in the sur- 

 face would call into existence. 



Nor was this group, which includes all the anthracite beds, 

 without its proportion of dry land, as we find from the vege- 

 table remains accompanying that carboniferous deposite, and 

 which have a common character both in North America and 

 Ireland. The equisetacece, or horse-tail tribe, not of the limited 

 height of recent plants of this family, three or four feet high, 

 but many of them equalling forest trees in size. A prepon- 

 derating number of /dices, or the fern tribe, both herbaceous 

 and arborescent. The lycopodiacea, or club-moss tribe, there 

 also attained a size equal to existing forest trees, whilst their 

 puny recent representatives are seen creeping, as it were, in a 

 moss-like form, not more than two or three feet long, over the 

 beds where their gigantic predecessors are entombed. All 



