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other kinds, and thirteen are found living only in sand. Here, for 

 the most part, among the sand-lovers, each species is not the only 

 one of its genus, as is the case with more than half the mud-lovers. 

 So there is this evidence that a good many more species live in the 

 sand than in the mud. A few species prefer shelly bottom, and occa- 

 sionally one is mentioned as having been found on rocky bottom or 

 shore, but never rocky alone always some other kind in addition to 

 the rocky. This is well, for there is no evidence of a rocky shore's 

 existing along the South Carolina coast either in Recent or Pleisto- 

 cene times. It is seen, at Young Island and Stono River, the two 

 places which furnish by far the greater number of species, that the 

 beds of shells have quantities of sand containing mud or clay mixed 

 with them. At one or two other places in the State the mixed-in 

 material is pretty much all mud or clay, as is the case at Maxyck 

 Ferry on the Santee, where a few species, like Mulinia lateralis, have 

 been found. This is just what our tables would lead us to expect. So 

 the conclusion here, as reached by a study of life- forms and of 

 actual beds as found, is that, though mud-loving species are found 

 in abundance, and also some lovers of shelly bottom, yet the weight of 

 evidence is in favor of a sandy bottom and shore for the Pleistocene 

 sea. Before leaving this phase of the subject, it is well to note that, 

 of the mud-loving forms, some species are very abundant as Pleisto- 

 cene fossils. Rangia cuneata is found in very great abundance un- 

 derneath Charleston, whole beds being made up of it down about 

 fifteen feet beneath the surface. Now, this is one of the estuarine 

 forms, and probably indicates that at one time during the Pleistocene 

 Period, the Ashley and Cooper rivers flowing into a somewhat land- 

 locked bay as they do today, there was much mud and brackish-water 

 conditions that just suited Rangia cuneata. Up the Potomac from 

 Cornfield Harbor, Maryland, about eighteen miles, is found an ex- 

 tensive bed of this species. Now, at Cornfield Harbor, Rangia cune- 

 ata is found, but is rare. The supposition here is that the water was 

 brackish enough at that distance up what was then an estuary as to 

 just suit this species and too brackish for much of anything else, that 

 while the deposit was being formed at Cornfield Harbor under marine 

 conditions that farther up the river was being formed under 

 estuarine conditions. In regard to the South Carolina Pleistocene 

 forms, it may be said that Rangia cuneata is only one of a half-dozen 

 that may have had just such estuaries with brackish water to live in. 

 With the exception of this species, the estuarine species are not at all 

 abundant in the Pleistocene localities of the State; indeed, three of 



