on the Fossils of the older Deposits in the Rhenish Provinces. 313 



found in Yorkshire, in the neighbourhood of Bristol, and in Tournay. The Platy- 

 crinites, of which nine are Devonian, fifteen Carboniferous, and three common to 

 both systems, are found particularly in the mountain limestone of England and 

 Belgium, and in the limestones of Devonshire and the Eifel. The twenty-three 

 species of Actinocrinites are, on the contrary, equally disseminated in the three 

 systems, and are met with in England, in the Eifel, upon the banks of the Rhine, 

 and in Sweden. Three are Devonian and Carboniferous, and one is quoted from 

 the province of Bolivia*. The Cyathocrinites have nearly the same geological 

 distribution : of the twenty-seven species known to us, nine are Silurian, from 

 England, Scandinavia and the adjacent islands ; ten are Devonian, from the 

 south-west of England, from the Eifel, and from Elbersreuth ; and lastly, four- 

 teen are Carboniferous, from England, Belgium, and the beds of the same age 

 in the centre and south of Russia. Two species, the C. pinnatus, Goldf., and C 

 rugosus, Miller, are common to the three systems. The Melocrinites of Goldfuss 

 (one only excepted from the mountain limestone of Stolberg) are all Devonian, 

 from the Eifel ; and the same may be said of the Rhodocrinites, one of which {R. 

 verus) is quoted by Goldfuss in the Eifel (Petref.), and by de Buch in the De- 

 vonian beds of Russia (Beitrage Russl. p. 62). 



On recapitulation we observe that the species of Crinoidea increase from the 

 lower toward the upper series in the proportion of 42 : 59 : 75. There is only one 

 species common to the two lower systems, while on the other hand ten belong to 

 both the Devonian and Carboniferous systems, a circumstance exactly the reverse 

 of what we have remarked of the Polyparia. 



VI. Annelida. — This class of animals appears to have been but very slightly de- 

 veloped during the older periods, if we may judge by the paucity of their remains ; 

 possibly the erratic species and those which live in sand may have existed in great 

 numbers without having left any traces, while only those which secreted calcareous 

 coverings, as the SerpulcE, though perhaps not more abundant, have been preserved 

 to the present age. Four species of SerpulcB are pointed out in the Silurian systemf , 

 six occur in the Devonian, and two in the Carboniferous. 



VII a. Conchifera dimyaria. — The great difficulty of becoming well acquainted 

 with the inside of bivalve shells, such as the hinge, the muscular impressions and the 

 palleal impression, which are so rarely well preserved in the deposits with which we 

 are occupied, should induce caution in admitting the generic approximations and 

 decisions that have hitherto been made ; nevertheless we have been led to adopt 

 the denominations which have been assigned to them by authors in consequence 

 of the impossibility of verifying the generic characters and the specific distinc- 

 tions of a great number of these shells. 



* D'Orbigny, Voyage dans TAmer. MIridionale. f Silur. Syst. p. 700. 



