BUFFALO SOCIETY OF NATURAL SCIENCES 1 99 



with fossils of marine origin, in no wise indicates that the merostomes 

 were marine. The Siluric fauna of Bohemia is one of the best illus- 

 trations of this class, and I shall consider it in detail. 



Barrande's work on the faunas of the Palaeozoic rocks of Bohemia 

 has conclusively shown that the trilobites and other Crustacea, as 

 well as the eurypterids reached their acme in numbers in the Siluric, 

 constituting the third fauna E. The upper part of this showed a far 

 more prolific development of life than did the lower, as is readily 

 brought out by the following figures. In the Lower Siluric (E ei) 

 Barrande records sixteen species of trilobites and ten species of other 

 arthropods among which he includes phyllopods, ostracods, euryp- 

 terids and cirripedes ; for the Upper Siluric (E e 2 ) the corresponding 

 figures are 82 and 24, making a total of Crustacea (and eurypterids) 

 for the Lower Siluric of 26, for the Upper 106. Furthermore, the 

 Crustacea, though represented by so many species were not the domi- 

 nant forms of life, for the Siluric, especially the upper part, marked 

 the period of greatest development of the cephalopods which were 

 represented by 665 species. As I stated in an earlier part of the 

 paper, Barrande does not give horizons of smaller taxonomic value 

 than his "bands" which correspond to the first subdivision of the 

 periods, and it is therefore impossible even to approach the niceties 

 of correlation which can be attained in America; one cannot deter- 

 mine the precise level even within several hundred feet for any par- 

 ticular occurrence. However, there is no reason to doubt that all 

 of the Siluric of Bohemia was marine. Considering the nature of the 

 fauna of that period and the number of species which Barrande was 

 able to describe even so early as 1852, his explanation for the frag- 

 mentary character of the eurypterids, as due to their having been the 

 food of the cephalopods, seems inadequate. If the trilobites were 

 able to live in the same sea with cephalopods and escape unscathed, 

 so that their remains were preserved in wonderful perfection, why 

 should the eurypterids have been so voraciously attacked? It is 

 doubtful if the eurypterids were, of so different an internal nature 

 from the trilobites that they should have been more palatable, nor 

 were their exoskeletons more fragile. In the Siluric sea 814 species 

 of cephalopods are known to have existed, as compared to 97 species 

 of trilobites. Thus there were eight or nine species of Cephalopods 

 to each species of trilobite, while the number of the individuals of the 

 former vastly exceeded that of the latter. Surely in the great strug- 

 gle for existence which was taking place, the cephalopods, if they fed 



