on the Fossils of the older Deposits in the Rhenish Provinces. 309 



We will now take a general survey of these several classes successively, com- 

 mencing with the more simple and ascending to the more complicated beings. We 

 shall point out the principal genera which they contain, their predominance in any 

 one of the systems or in any country, and we shall follow, so to speak, their distri- 

 bution over the surface of the globe during these three great periods, which com- 

 mence with the first traces of life and end with the Magnesian Limestone* of 

 England (the Zechstein of Germany, or Permian system of Russia). See letter of 

 Mr. Murchison, Phil. Mag. 



In presenting this abridged Table of our present knowledge, we do not forget 

 that researches will produce some changes in our numbers, and may modify the 

 relations which we have established ; but this is the necessary consequence of 

 the progress of science, and we shall only rejoice at it : as the errors of determina- 

 tion must be proportioned to the number of species, the results will not be sen- 

 sibly altered by them. 



General Remarks on the several Classes. 



I. Incertce Sedes. — The remains of organic origin, the characters of which, far 

 removed from those of all known types, do not permit us to assign them their pro- 

 per place in the series, must naturally belong to the most ancient beds, and, in 'fact, 

 it is in the older slaty schists of Carmarthenshire that the serpuliform bodies, re- 

 garded by MacLeay as sea- worms, and to which Mr. Murchison has given the names 

 of Nereites, Myrianites, and Nemertites, are found. The Polymeres Demetarum of 

 the same author belongs to the Llandeilo beds. The Graptolites or Prionotus (of 

 which fifteen species have been pointed out, undoubtedly too many, as Dr. Beck 

 thinks) belong to the Silurian system, both in Europe and in North as well as 

 South America, and the greatest number of them are peculiar to the lower beds 

 of the system. It is probable that the Annulites which Mr. MacClelland found in 

 India in the mountain district between Lohooghat and Almorah, in the province of 

 Kemaon, belong also to the most ancient depositsf . As to the Tentaculites, they 

 ascend through all the Silurian beds, and penetrate even into the Devonian lime- 

 stone of the Eifel and their equivalents, both in Europe and in North America. One 

 species has been pointed out in the south of Africa. The Cophinus and Spongiarium 

 belong to the Ludlow beds ; and lastly, the Receptaculites Neptuni, Defr. j {Ischadites 

 Konigii, Murch.), which is also found in the Ludlow beds, may likewise be seen in 



* Although we completely adopt the views of Mr. Phillips in considering the Magnesian limestone as 

 containing organic forms of the Carboniferous system, and though we extend this view to the Zechstein 

 and to the Permian system, nevertheless the species of these latter beds have not yet been compared 

 with sufficient care by hs to be comprehended in the following considerations. 



f Journ. Asiatic Soc. Bengal, vol. iii. p. 628, and vol. iv. p. 520. 



+ Diet. Sc. Nat. tome xlv. p. 5. 

 VOL. VI. — SECOND SERIES. 2s 



