56 



investigations have been made into the present fauna of the south- 

 eastern Atlantic coast of the United States. But, as it is, we have a 

 reconfirmation that the beds here considered are without doubt Pleis- 

 tocene. It is further seen that about 60 per cent, of these Pleistocene 

 species are also found in the Pliocene of the neighboring regions. 

 This shows that the transit from Pliocene to Pleistocene times and 

 conditions brought no great or sudden changes with it in South 

 Carolina. The probability is that, with the advance of the ice-sheet 

 from the north into the latitude of New Jersey, the accompanying 

 cold was a long time reaching South Carolina, and there was no 

 widespread destruction of Pliocene forms on this part of the coast 

 whatever may have been the effect produced farther north. This 

 phase of the subject will come up later in the discussion, and need 

 not be dwelt upon here. It may also be observed that about 30 per 

 cent, of the species are also Miocene. This is about what we might 

 expect if there had been no great or sweeping changes, and if only 

 the ordinary forces of evolution had been at work combined with 

 moderate changes in environment. Only occasionally is a form seen 

 to run back into the Oligocene or the Eocene one proof that the 

 transition from Oligocene to Miocene conditions was accompanied 

 by influences more destructive to life than have been those of any 

 transition since that time. 



In accord with well-recognized and almost universally adopted 

 principles, it is assumed, without taking the time to prove it, that any 

 given species lives under approximately similar conditions of tem- 

 perature, depth, shore or bottom, salinity, current, or other environ- 

 mental condition in whatever geologic age it has been found. For in 

 case the species, as has just been said, should little by little be changed 

 with gradual advances into a distinctly different habitat to such a 

 degree as to be clearly distinguishable from what it was originally, 

 then it comes to be no longer regarded as the same species, but as a 

 new species, distinct from the old. Therefore, with respect to the 

 matter in hand, it is safe to assume that a species had, in the main, 

 the same conditions of temperature, the same kind of bottom, the 

 same fondness for or aversion to salt water or brackish water, or to 

 a shore of vigorous waves or a region of quiet, or to shallow water or 

 deeper, etc., in the Pleistocene Period that it has today. Now, these 

 conditions for recent forms have been fairly well worked out by 

 Verrill and Smith on the southeastern coast of New England, and 

 by others along the Atlantic coast farther south, whose work has 

 been tabulated by Dall in Bulletin 37 of the Proceedings of the Na- 



