on the Fossils of the older Deposits in the Rhenish Provinces. 325 



presents numerous varieties in the limestones of Paffrath, as well as the B. Schlo- 

 theimii, nob., which is also found in the corresponding beds of Devonshire. Those 

 shells of the older beds which have been united to Buccinum, differ nevertheless 

 in the characters of the aperture sufficiently to authorize the establishment of the 

 subgenus proposed by Phillips under the name of Macrocheilus* . With respect to 

 the other genera of Gasteropods which have been noticed as represented in the 

 first sedimentary beds, we think it right to say that they are only approximations 

 too incomplete to be mentioned here. 



In considering collectively the number of species of this class distributed in each 

 system, a very decided increase from below upwards may be observed, for there are 

 63 Silurian, 116 Devonian, and 225 Carboniferous ; a progression which appears to 

 have been continuous to the present time, notwithstanding some local and momen- 

 tary interruptions in the secondary periods. 



VIII b. Pteropoda. — We refer provisionally to this class the genus Conularia, of 

 which we know eleven species ; or six Silurian, four Devonian, and two Carbo- 

 niferous. The C. quadrisulcata, Sow., belongs to the uppermost system only, having 

 been wrongly noticed as belonging to the more ancient beds. The Conulariee are 

 spread over the various parts of Europe and North America, and are also found in the 

 south of Africa : they do not appear to show themselves above the coal-measures. 



VIII c. Heteropoda. — Bellerophon is a genus peculiar to the Palaeozoic deposits of 

 the several epochs, in which specimens are more or less extensively distributed. As 

 in the preceding genera, the species peculiar to any one system are usually found 

 only in a few localities, and consequently it must very rarely happen that any one 

 species should characterize a system through any great extent of country. Fifteen 

 are Silurian, twenty-one Devonian, and six are common to the two series. Among 

 these we shall mention the B. Murchisoni, d'Orb., of the tilestone or lowest stratum 

 of the old red sandstone of England f , and which is also found in the slates of 

 Wissenbach ; then the B. trilobatus, Sow. (in Murch. Sil. Syst.), B, carinatus, id., and 

 B. acutus, id. The last, which belongs to the lower Silurian beds of England, reappears 

 in the limestones of Elbersreuth, and is found in the ancient beds of Southern Africa. 

 The Carboniferous system is still richer than the preceding ; it contains thirty-six 

 species, which are very common in the mountain limestone of Scotland, Ireland, 

 England, Belgium, and of the north and centre of Russia. The B. Verneuilli, d'Orb., 

 of Vise has been likewise found in the Altai. Lastly, the B. Urii, Fleming, {B. Atlan- 



* Palaeozoic Fossils of Cornwall, &c., p. 103 et seq., 184-1. 



t We are informed by Mr. Murchison that he has no objection to admit his tilestone group of the Old 

 Red or Devonian system into the Silurian system. Indeed in his work he shows by the fossils that these 

 tilestones are beds of passage between the two systems, and that they were grouped with the Old Red 

 chiefly on account of their geographical position, structure and colour March 1842. 



VOL. VI. SECOND SERIES. 2 U 



