Br. H. Hichs — Life Zones in Palceozoic Rochs. 443 



If we now add to tbese the Annelids which had been previously 

 discovered in these rocks, we have at least seven orders represented 

 in this fauna, the earliest at present known. These same groups 

 are also more or less present and tend to characterize these early 

 deposits wherever found ; but no country has, up to the present 

 time, produced a more varied fauna or a greater richness in types 

 than England. Scandinavia has a larger number of species, but 

 not so many groups." I then give a table showing the number of 

 '■' forms discovered in the Lowest or Paradoxides Zone in different 

 parts of the world," from which " it will be observed that England 

 has produced eight of these groups, whilst none of the other 

 countries has yielded more than five. It is, however, most interest- 

 ing to note the similarity of types in regions so far apart, and the 

 close resemblance of the faunas." The researches which have been 

 carried on in the Cambrian rocks since that time, though they have 

 added greatly to the number of forms, especially in America, owing 

 to the labours of Mr. Ford, Mr. G. F. Matthew, Mr. C. D. Walcott, 

 and others, have mainly strengthened the evidence in regard to the 

 similarity of types. The still earlier faunas since made out in 

 Scandinavia, Eussia, and America also show that the following- 

 conclusions given in my paper were, in the main, fully warranted : 

 " The fact also that Trilobites had attained their maximum size 

 at this period, and that forms were present representative of almost 

 every stage of development, from the little Agnoshis with two 

 rings to the thorax, and Microdiseus with four, to Erinnys with 

 twenty-four, and blind genera along with those having the largest 

 eyes, leads to the conclusion that, for these several stages to have 

 taken place, numerous previous faunas must have had an existence, 

 and, moreover, that even at this time, in the history of our globe, 

 an enormous period had already elapsed since life first dawned upon 

 it." In so minute a subdivision as I at first adopted it was scarcely 

 to be expected that the zones would be of equal value ; but the plan 

 nevertheless often furnished information of much interest. For 

 instance, in one section at what appeared to be a new horizon a 

 form of Paradoxides was found which seemed to diifer materially 

 from the Paradoxides (P. HicJcsii) in the next zone, and I was only 

 able to satisfy myself that it was a young specimen of that species 

 by finding others showing intermediate stages in association with 

 fully grown specimens. Five main zones characterized by new 

 species of Paradoxides were made out, and in each of these new 

 species of the more important associated forms also occurred. 

 Though five species of Paradoxides only were made out at St. 

 David's, three species of the very closely allied genera Plutonia 

 and Anopolenus were also discovered. Plutonia, characterized mainly 

 by its spinous ornamentation and wide ribs, a Trilobite of gigantic 

 size, equalling, if not exceeding, the largest Paradoxides, must have 

 been a formidable-looking Crustacean in these early seas. Hitherto, 

 it has only been found at the base of the Middle Cambrian at St. 

 David's, and one species only has been discovered. The largest 

 Paradoxides {P. Daoidis), on the other hand, occurs in the highest 



