THE CARRONIFEROUS. ] .') 



genus Naiadites. Mr R. Etheridge, Jr., of the Geological Survey of 

 Great Britain, has summed up the evidence as to the true nature of 

 these shells, and has revised and added to the species, in a series of 

 articles in the Geological Magazine of London, vol. viii. 



If we exclude tlie alleged Fla^iorbis above referred to, all the 

 Palaeozoic Pulmonifera hitherto found are American. Since, however, 

 in the Carboniferous age, Batrachians, Arachnidans, Insects, and 

 Millipedes occur on both continents, it is not unlikely that ere long 

 European species of land snails will be announced. The species 

 hitherto found in Eastern America are in every way strangely 

 isolated. In the plant-beds of St John, about 9000 feet in thickness, 

 and in the coal-formation of the South Joggins, more than 7000 feet 

 in thickness, no other Gasteropods occur, nor, I believe, do any 

 occur in the beds holding land snails in Illinois. Nor, as already 

 stated, are any of the aquatic Pulmonifera known in the Paheozoic. 

 Thus, in so far as at present known, these Palaeozoic snails are 

 separated not only from any predecessors, if there were any, or 

 successors, but from any contemporary animals allied to them. 



It is probable that the land snails of the Erian and Carboniferous 

 were neither numerous nor important members of the faunas of those 

 periods. Had other species existed in any considerable numbers, 

 there is no reason why they should not have been found in the erect 

 trees, or in those shales which contain land plants. More especially 

 would the discovery of any larger species, had they existed, been 

 likely to have occurred. Further, what we know of the vegetation 

 of the Palaeozoic Period would lead us to infer that it did not abound 

 in those succulent and nutritious leaves and fruits which are most 

 congenial to land snails. It is to be observed, however, that we know 

 little as yet of the upland life of the Erian or Carboniferous. The 

 animal life of the drier parts of the low country is indeed as yet very 

 little known ; and but for the revelations in this respect of the erect 

 trees in one bed in the coal-formation of Nova Scotia, our knowledge 

 of the land snails and Millipedes, and also of an eminently terrestrial 

 group of reptiles, the Microsmcna, would have been much more im- 

 perfect than it is. We may hope for still further revelations of this 

 kind, and in the meantime, it would be premature to speculate as to 

 the affinities of our little group of land snails with auiuials either their 

 contemporaries or belonging to earlier or later formations, except to 

 note the fact of the little change of form or structure in this type of 

 life in that vast interval of time which separates the Erian Period 

 from the present day. 



In 187S, a small grant having been given by tlio Jvoyal Society of 



