Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/589

 was also not more than forty miles from land. The species of Mollusca also procured in this dredging were extremely remarkable, and many were quite new to him. They were, however, living or recent species ; none of them were Eocene or Miocene, much less Cretaceous, like Terebratula caput-serpentis. He quoted from Mr. Davidson instances of the persistence of Brachiopoda, especially of the genus Lingula from the Silurian formation: The continuance of this species of coral, as well as of certain Foraminifera, from the Cretaceous to the present time was therefore not exceptional ; and other cases of survival from even earlier times might eventually be recognized.

Dr. Carpenter, after commenting on the reductions that extended knowledge enabled naturalists to make in the number of presumed species, could not accept the mere identification of species as of the highest importance in connecting the Cretaceous fauna with that of our own day. The identity of genera was, in his opinion, of far more importance. He instanced Echinothuria and Rhizocrinus as preserving types identically the same as those of a remote period, and as illustrating the continuity of the deep-sea fauna from Cretaceous times. The chemical and organic constitution of the deep-sea bottom of the present day was also singularly analogous to that of the Chalk sea. The low temperature at the bottom of the deep sea, even in equatorial regions, was now becoming universally recognized; and this temperature must have had an important bearing on the animal life at the sea-bottom.

Prof. Ramsay thought that there was some misapprehension abroad as to the views held by geologists as to continuity of conditions. They had, however, always insisted on there having been an average amount of sea and land during all time ; and the fact of sea having occupied what is now the middle of the Atlantic since Cretaceous time would create no surprise among them. If, however, the bed of the Atlantic were raised, though probably many Cretaceous genera, and even species, might be found, there would on the whole be a very marked difference between these Atlantic beds and those of the Chalk.

Mr. Seeley had already, in 1862, put forward views which had now been fully borne out by recent investigation. His conviction was that, from the genera having persisted for so long a time, the genera found in any formation afforded no safe guide as to its age, unless there were evidence of their having since those formations become extinct.

Mr. Etheridge maintained that the species in different formations were sufficiently distinct, though the genera might be the same. Recent dredgings had not brought to light any of the characteristic molluscan forms of the Cretaceous time ; and it would be of great importance to compare the results of future operations with the old Cretaceous deep-sea fauna.

Prof. Rupert Jones, with reference to the supposed sudden extinction of chambered Cephalopods, remarked that Cretaceous forms had already been discovered in Tertiary beds in North America, and also that cold currents could not have destroyed them, seeing that icebergs came down to the latitude of Croydon in the Chalk sea.