556 H. HICKS ON THE DEPOSITION OE THE 



and that they were deposited regularly over a gradually subsiding 

 area, we evidently ought to find some evidence here to prove the truth 

 or fallacy of the evolution theory as to the beginning of life and 

 subsequent development. The picture offered to my mind in the 

 consideration of these early forms of life is one most strongly in, 

 favour of such views ; and the evidence seems both clear and con- 

 vincing. Taking the three earliest faunas together, which are all 

 in the Lower Cambrian rocks, we find the following seven great 

 groups present : — Annelides, Brachiopods, Trilobites, Ostracods, 

 Cystids, Sponges, and Pteropods. With regard to the first five, if we 

 are to believe biologists such as Fritz Miiller, Hackel, and others, 

 the evidence is most strong, not only that they are very nearly allied, 

 but also that they could easily, and without undergoing any very 

 great changes, have been derived from one common form. Of the 

 other two the Sponges are of so inferior a grade that they may pro- 

 bably have dated back to the time of the Eozoon, whilst the Ptero- 

 pods found are so simple in their structure that we may look upon 

 them as being early offshoots from which may subsequently have 

 been developed the Cephalopods and Gasteropods. These early forms 

 tenanted the seas when the Laurentian continents alone existed, 

 and before even a bed of our Cambrian rocks, as now exposed to 

 us, was deposited ; and if there were no other higher forms in more 

 favoured spots, and nearer to the original home, these are ample to 

 show that a long period must even then have been passed over 

 before this progress could have taken place. It does not appear 

 in any way necessary that these were the highest forms in existence 

 at this time ; and, indeed, it seems more reasonable to think that they 

 were not, and that higher forms were even then ready to migrate, 

 if not already on their way ; for when the seas along these areas are 

 again sufficiently deep for an easy passage forward, a much higher 

 fauna appears, and the higher invertebrates, the Cephalopods, Gaste- 

 ropods, and Lamellibranchs, are found along with the groups which 

 had appeared in the earlier faunas. It is an interesting fact and 

 one which tends to show the line of migration, that these again 

 appear in the western (or Welsh and Spanish) areas at a much earlier 

 period than in the eastern. The time which must have elapsed, 

 according to present evidence, between the appearance of the lower 

 invertebrate fauna in the Longmynd Group and of the higher fauna 

 in the Tremadoc Group must have been great, as it means the depo- 

 sition of at least from 8000 to 10,000 feet of beds ; and though this 

 may not have been sufficient to allow for all the changes in tte 

 forms, yet it was quite sufficient for the migration to have taken 

 place even at a slow rate. 



There is much other and additional evidence of this nature to be 

 found by the examination of these early faunas. The western areas 

 have a larger number of orders, a greater number of genera," and in 

 the genera show a greater number of varieties or stages of pro- 

 gression than we find in any of the more eastern areas. Many of 

 these steps or species are wanting in the eastern areas ; and it is 

 probable that they never reached so far, just as it is evident 



