on the Fossils of the older Deposits in the Rhenish Provinces. 307 



Mr. J. Phillips thinks that the Testaceous Mollusks preceded the Polyparia ; but it 

 may be remarked that limestones are rare in the oldest beds, which are almost always 

 formed of slates, grauwacke, or quartzite, then in a state of more or less argillaceous 

 mud and of more or less impure sand, sometimes fine, sometimes coarse, constituting 

 an unfavourable foundation for the stony Polyparia ; but this does not follow in 

 relation to the naked, the gelatinous, the phytoid or corneous Polyparia, or even 

 other more elevated beings, such as the Medusaria, which may have existed before. 

 If the waters of this first period contained very little carbonate of lime, and if this 

 cause have also contributed with the preceding to the rarity of the stony Polyparia, 

 it must also have had some influence over the Testacea. These latter also would 

 only have appeared when circumstances had become more favourable, and they 

 might have been preceded by a great quantity of soft animals, such as the Actinia; 

 an hypothesis which would moreover be confirmed by the bituminous matter con- 

 tained in many rocks in which we do not find any organic remains. As to the 

 silex, it does not appear to have been found in these waters in a favourable state 

 for the existence of sponges, which are rare in these ancient deposits comparatively 

 with what are observed in the secondary periods. 



The first seas have been said to have been but of small depth, and that the tem- 

 perature, being more uniform than it is now, there resulted a greater uniformity, 

 both organic and inorganic, in the character of the deposits ; and it is added, that 

 it is only in consequence of the upraising of the beds that the asperities of the 

 globe's surface became more distinct, the seas deeper, external circumstances more 

 varied, and animalization also more diversified. If the mineral characters of the 

 ancient rocks were more similar to each other than those of the following periods, it 

 may be attributed to the circumstance, that all the primary sediments resulted from 

 the alteration and decomposition of crystallized rocks differing very slightly in their 

 elementary composition. As to the greater uniformity of the organized beings, it 

 will appear much less decided than it has long been thought, if, as we are about to 

 do, the animals of each great class be considered successively. And lastly, the 

 slight depth of the seas, deduced, according to Conrad's notion, from the absence 

 of Cephalopods with an involute shell, is on the other hand contradicted by the 

 presence of gigantic Cephalopods with a straight and very fragile shell, which could 

 only live in the great ocean and in very deep waters. 



The French translation of the Manual of Geology by Mr. De la Beche, which ap- 

 peared in ] 833, contains lists of fossils which at that time were considered rather 

 extensive. These lists comprehend 589 species, distributed in the coal-measures 

 (properly so called), in the carboniferous limestone, and in the grauwacke group. 

 At present, the same series of beds, constituting the Carboniferous, the Devonian, 

 and the Silurian systems, present, after deducting the repetitions, 2698 species of 



