158 HISTORICAL PALAEONTOLOGY. 



shallow water and littoral deposits of the period, while in the 

 other we are introduced to the deep-sea accumulations of the 

 same period. Nor can the problem at issue be solved by an 

 appeal to the phenomena of the British area alone, be the 

 testimony of these what it may. As a matter of fact, there is 

 at present no sufficient ground for believing that there is any 

 irreconcilable discordance between the succession of rocks 

 and of life in Britain during the period which elapsed between 

 the deposition of the Upper Ludlow and the formation of the 



Fig. 106. Holoptychiua nobilissimus, restored. Old Red Sandstone, Scotland. 

 A, Scale of the same. 



Carboniferous Limestone, and the order of the same phe- 

 nomena during the same period in other regions. Some of 

 the Devonian types of life, as is the case with all great forma- 

 tions, have descended unchanged from older types; others 

 pass upwards unchanged to the succeeding period : but the 

 fauna and flora of the Devonian period are, as a whole, quite 

 distinct frdm those of the preceding Silurian or the succeeding 

 Carboniferous ; and they correspond to an equally distinct 

 rock-system, which in point of time holds an intermediate 

 position between the two great groups just mentioned. As 

 before remarked, this conclusion may be regarded as suffi- 

 ciently proved even by the phenomena of a British area; 

 but it may be said to be rendered a certainty by the study of 

 the Devonian deposits of the continent of Europe or, still 

 more, by the investigation of the vast, for the most part un- 

 interrupted and continuous series of sediments which com- 

 menced to be laid down in North America at the beginning of 

 the Upper Silurian, and did not cease till, at any rate, the close 

 of the Carboniferous. 



