278 PEOCEEDIlIirQS OP THE GEOLOGICAL SOCIETY. 



From Upper Devonian (besides recurrents from below and abeady 

 emimerated) — 



Fenestella laxa. Spirifer lineatiis. 



Leptsena analoga. Terebratiila pleurodon. 



Productus laxispiniis. Loxonema tumida. — (6.) 



The following points are worth recording: — The proportion of 

 Devonian recurrents in Europe generally, according to the Table 

 of De Yerneuil and D'Archiac, is -j^ths of the whole, which is con- 

 siderably greater than the -jH^-ths which we found to rule in New 

 York. Thirty-four out of 207 European recurrents (Devonian) are 

 met with in New York (and 4 more in Ohio and Tennessee), with, in 

 many cases, considerable vertical range. One-sixth of these Devonian 

 recurrents being thus common to both continents indicates a strong 

 affinity between their respective palaeozoic basins ; and the fact ob- 

 tains additional force when we remember how very dissimilar 

 palaeozoic provinces, far nearer geographically, are in Europe. In 

 both hemispheres all the orders and most of the genera have their 

 representative recurrents ; and they are principally BracMopoda, 

 Gasteropoda, Lamellibranchiata, and Zoophyta. 



§ 4. On the Grouping of Fossils, and their Order of Precedence. — The 

 Invertebrate species of the palaeozoic strata of New York, and of all 

 other examined regions, were purposely grouped by the Creator in 

 societies on their respective horizons, and were adapted to live 

 among a complicated balance of agencies, favourable and unfavour- 

 able. There was a predetermined harmony in the mutual relations 

 of the new beings, and a predetermined amount and kind of sus- 

 tenance provided, such sustenance being derived ultimately from the 

 sediments and the water in which they existed. Different assem- 

 blages of forms prevailed in each sediment, according to its mineral 

 constitution ; so that certain New York group-sections, far removed 

 from each other vertically, are yet peopled by the same genera at 

 least, and often by the same species. This is exemplified in a 

 striking manner by the argillo- calcareous strata of the Trenton and 

 Niagara sections, although not even in the same stages of the sj^stem. 

 Generically, both these sets of beds are tenanted conspicuously alike 

 by Annelida, Echinodermata, Zoophyta, &c. The Devonian strata, 

 Hamilton and Chemung, principally argillo-arenaceous, give similar 

 testimony. The races here are the same to a singular extent, and 

 even specifically, although separated by three horizons. The more 

 purely arenaceous sections of this Silurian basin, however, do not 

 agree so closely in their population, both from the ever-changing 

 nature of their lithological characters, and from the very various 

 periods of geological time, and other circumstances under which 

 they were laid down. We see aU this in the Calciferous Sandstone, 

 Medina Sandstone, and Onondaga-Salt group of New York. We 

 perceive, then, that the successive introduction of animal life was 

 not regulated by simplicity or by complexity of structure ; for both 

 have been contemporaneous from the beginning. Mutual suitabi- 

 lity, and, in a great degree, the dependence of the higher on the 



