104 PEOF. J. LOGAN LOBLEY, F.G.S., F.E.G.S., ON 



and the latest deposits, and all the species show wonderful 

 similarity. 



The space at my disposal will not allow of other illustrations 

 of the great fact of persistency of animal types, the numerous 

 examples of which are well known to students of palaeontology, 

 but the facts now stated are sufficient to show that animal life 

 has existed with similar forms and similar physiological powers 

 from the far-back Cambrian period to our own times. 



In the plant world, too, the persistence of types is conspicu- 

 ous. The oldest land-plants we know are ferns very like recent 

 ferns, and the LeiJidodeiidron, Sigillaria and Ccdamites of the 

 Coal Measures are lycopods and equisetums now abundantly 

 represented. 



This persistence of form, of structure, and of similar functional 

 capabilities of organs, clearly indicates generally similar inorganic 

 conditions to the present in Paheozoic times. It tells of condi- 

 tions of sea-water and atmosphere, of temperature and light, at 

 least not greatly differing from those we know, and shows, I 

 think, conclusively, that whatever marked cooling of the exterior 

 of the globe, and whatever consequent shrinkage of the globe has 

 taken place in the past, that cooling and that shrinkage took 

 place before the Cambrian, and I believe before the Pre- Cam- 

 brian, sedimentary rocks were formed by accumulation of 

 detrital matter. The evidence afforded by the Cambrian rocks 

 and the evidence afforded by the Cambrian fossils is indeed so 

 cogent that we are enabled to picture to ourselves the world in 

 Cambrian times. As I wrote some years ago :* we can see, as it 

 were, its lands and its seas, its spreading plains and elevated 

 uplands, with its broad and deep seas, and their shallower bays 

 and gulfs. On the land, too, are rushing torrents, ripiDling 

 streams, and larger and smoother flowing rivers, carrying eroded 

 material to the Cambrian ocean, fringed by sandy shores and 

 shingly beaches. And the sky above is now an unblemished 

 azure, now flecked with cirrus and now dark with nimbus. 

 Pain falls, winds blow, tides ebb and flow, and we can see the 

 broad expanse of waters in their calm majesty or angry with 

 storm and tempest, rolling mighty waves upon the Cambrian 

 strand, and we can think of the millions of splendid sun-risings 

 and gorgeous sunsets, and almost feel the heat of the noontide 

 sunnner sun or the cold of the niid-Avinter night. We can even 

 look through the clear salt-water on to the ocean bed, and see 



* Presidential Address to the City of London College Science Society, 

 1807. 



