310 Viscount cI'Archiac and M. de Verneuil 



the Silurian slates and the Devonian limestones of Belgium and the Eifel, as well 

 as the Pleurodyctium probleniaticum of Goldfuss*. 



II. Infusoria. — Numerous remains which evidently belonged to animals of this 

 class have been recognized by M. Ehrenberg in the silex of the carboniferous for- 

 mation collected by M. Helmersen upon the banks of the Volga in the vicinity of 

 Twer. This very recent observation, not yet published, confirms our views rela- 

 tive to the development of organized beings on the surface of the globe. 



III. Polyparia. — We are not aware of the existence of any naked Polyparia in 

 the oldest beds. Of Corallines, the CellaricB and the Sertularics appear very rarely, 

 whether the traces of them have disappeared, or whether these animals were actu- 

 ally few in number. The Spongiaria, as well as the reticulated Polyparia, are but 

 little spread in them comparatively with the stony Zoophytes. Among these latter 

 we shall mention the Stromatopora, of which one species in particular, the Str. con- 

 centrica, Goldf., is very abundant in the Silurian and Devonian deposits in England, 

 in the Eifel, and in the Rhenish provinces ; also on both sides of the Ural, and in 

 the state of Tennessee in North Americaf. The Retepora were particularly de- 

 veloped during the Carboniferous period ; but the species from which the genus 

 Fenestella has been formed, are more numerous in the Dudley and Wenlock beds 

 than in their equivalents of Gottland and Esthonia. Two of these species pass 

 into the Devonian system. The GorgonifB are not uncommon in the Palaeozoic 

 rocks. One of them, the G. ripisteria, Goldf., appears to have lived during the 

 three periods. The Lithodendron is more particularly seen in the last of them ; 

 the Cystiphyllum in the two first in England, and in the Devonian system in Bel- 

 gium and in the Eifel. 



The great genus Cyathophyllum, such as it is established by Goldfuss, is one of 

 the most important, as well on account of the number of species as for their pro- 

 fusion in all the periods, and the presence of some of them in the most distant 

 countries. Nine species are Silurian, seventeen are Devonian, and eight are 

 Carboniferous ; and six are common to the two first systems. 



It is particularly in the Devonian rocks upon the banks of the Rhine and 

 in the Eifel that this genus is most extended. It is also very plentiful in the 

 Silurian rocks of Scandinavia, and in North America upon the banks of Lake 

 Huron, likewise in the states of Ohio, New York and Tennessee. It is to be 

 observed that this genus is a dismemberment from the true Astrea, which, with 



* M. Goldfuss, Petref. vol. ii. p. 286, has inquired whether this organic body may not be referrible to 

 the MoUusca ; being of opinion that it was an animal of that class provided with foliaceous branchiae, 

 and had the power of affixing itself to shells. 



f Memoir on the Organic Remains in the Valley of the Mississippi, Trans. Geol. Soc. Pennsylvania, 

 vol. i. part 2. p. 248. » 



