OF THE CARBONIFEROUS SERIES. 041 



[America. — I am unwilling to lengthen this paper by reference to 

 the succession of beds on the American continent, but think it 

 proper to observe that, as Dr. Ferd. ltomer has pointed out, the 

 marine stage, E, is fairly represented at the base of the Coal-measures 

 in the United States *. In the lower beds of the productive Coal- 

 measures in the western portion of the State of Kentucky occurs a 

 small Lingula (L. umbonata, Cox), which Dr. Homer considers to be 

 in all probability identical with L. mytiloides of Phillips ; and about 

 100 feet higher in the series, at Nolin Iron- works, several genera of 

 Cephalopods also are found. Amongst these is Nautilus ferratus, 

 Cox, which approaches very closely to, if it be not identical with, 

 N. bilobatus, Sow., from the Carboniferous Limestone of Coalbrook- 

 dale. 



In the State of Iowa, a band of marine limestone occurs about 

 20 feet above the " Concretionary Limestone " which marks the 

 upper limit of the Carboniferous Limestone proper. It is separated 

 from this latter by shales, sandstones, and a bed of coal 15 inches 

 thick. In this limestone are found several species of Productus, a 

 small Spirifer, a Nautilus, and the tail of a Trilobite t. Similar 

 marine bands are found in the districts lying at the base of the pro- 

 ductive Coal-measures, and may be regarded as referable to the 

 horizon of the Lower Coal-measures of the British Isles. 



Even if America afforded no analogy as regards the succession of 

 beds with that of Britain, it ought not to be considered as invali- 

 dating the views here expressed. The British and continental areas 

 are sufficiently large to form the basis for a classification of beds.] 



Part VI. 



(a) Conclusions regarding the Conditions of Deposition of Carboni- 

 ferous /Strata drawn from the Characters of the Fossil Fauna. 



Amongst the varieties of remains of animals which have been 

 found in various Carboniferous strata there are none upon which we 

 can rely with so much confidence for information regarding the con- 

 ditions of deposition as the Mollusca. Of those which lived in the 

 Carboniferous period many of the genera, or their modifications, 

 descend down to the present day ; so that we may determine their 

 habits by actual observation, and, by inference, those of their prede- 

 cessors. 



It is not so with the fishes. The placoids and ganoids of the Coal- 

 period were, in all probability, like the sturgeon and other inhabi- 

 tants of the Black Sea and the Caspian, migratory, and capable of living 

 either in the open ocean, or of navigating the streams and plant-choked 

 estuaries of the period ; so that they throw no light upon the condi- 

 tions of deposition of the strata in which their remains are found. 



* Loc. supra cit. p. 604. Quoting MM. E. T. Cox and Leo Lesquereux, 

 'Geological Keport of Kentucky,' vol. iii. pp. 515, 51G (1857). 



t 'Keport on the Geological Survey of the State of Iov.a,' by J. Kail and 

 J. D. Whitney, vol. i. p. 233 (1858). 



