APPENDIX. 99 



APPENDIX. 



THALASSA AND XEKA IN THE PERMIAN PEBIOD. 

 By Professor WILLIAM KING, Sc.D. &c. 



IN my ' Monograph of the Permian Fossils [of England 3 * 

 (1850) I expressed the opinion, based on the general character 

 of their respective groups of fossils, that the formations of the 

 Permian system had been deposited, some in shallow seas, and 

 others in a deep ocean. In using these expressions it was 

 meant to limit the application of the last one to depths known 

 to long-line fishermen, and ranging from 50 to 100 fathoms or 

 moref; for when this opinion was stated very little had been 

 published respecting the existence of living things in the abysses 

 of the great ocean. 



Further, in consideration o the fact that the Permian 

 formations occupy widely separated areas, I inferred that the 

 ocean (or seas) in which they were deposited was of considerable 

 extent, encompassing, at least, a great portion of the European 

 quarter of the globe. 



Investigations on Permian geology made during the last 

 thirty years have in no way invalidated these conclusions ; yet 

 Dr. Bamsay, in his f Physical Geology and Geography of 

 Great Britain/ and certain of his memoirs, has been induced to 

 interpret the evidences I relied on in a totally opposite sense. 



From the <( dwarfed aspect " of the Permian shells, and their 

 " poverty in number," it is Dr. Ramsay's " belief" that the 

 waters they lived in "were of an inland unhealthy nature/* 

 comparable to those of " brackish lakes " like the Caspian. 



Before discussing these points, it is necessary for me to 

 mention that I have lately (June 18, 1880) advanced the hypo- 

 thesis that the regions over which the different rock-systems 

 formulated by geologists are spread have each undergone, 



* Introduction, pp. xiii, xiv. 



t Several years ago I named a characteristic form of JSuccinum undatum^ 

 var. pdagicum, on account of its living at depths ranging from 55 to 

 80 fathoms (Ann. & Mag. Nat. Hist, 1846, vol. xviii. p. 249). 



H2 



