TRANSACTIONS OF WAGNER 

 1618 



TERTIARY FAUNA OF FLORIDA 



vertically intersected. Where the vertical and horizontal columns of a single formation 

 intersect the figures indicate the total number of species known from that formation. 

 Thus in horizontal column F (Duplin Miocene), at the intersection of vertical column J, 

 we find the number 18, which signifies that there are eighteen Duplin species also found in 

 the Chipola (J) Oligocene. Column S is merely approximate, the required data to make 

 it complete being inaccessible at present. Where no common species are known the 

 vacancy in the intersection indicates the fact, but it must not be inferred that some may 

 not eventually be found common to the two formations. In the column headed " Re- 

 cent" the number of species now known to survive in each horizon is entered. The next 

 column shows the number of species now known only from that formation, numbers 

 which future researches must inevitably add to. The next two columns give the " Recent" 

 and " Peculiar" species in percentages of the total fauna of the formation to the nearest 

 integer. In Bulletin 84 of the United States Geological Survey (pp. 25-31) I have dis- 

 cussed the question of the number of shell-bearing species of mollusks which is normal ' 

 to any one limited region. An actual count of the species found in less than one hundred 

 fathoms on the coast of the United States between Cape Hatteras, North Carolina, and 

 the mouth of the Savannah River affords the number of five hundred species. But in 

 any one limited locality, as a sand beach, a rocky shore, an estuary or a lagoon, no one 

 could find all these species. Certain kinds of terrain are more favorable to shells than 

 others ; an oyster-reef or a sand beach will always have less population than a shore of 

 mixed mud and gravel. So I have in the column headed " Normal Fauna" given the 

 best estimate that I could of the number of species which might be expected to occur 

 in the locality where collections had been made to illustrate the particular formation 

 referred to. The last column of the Table, headed " Fossil faunas per cent.," shows the 

 percentage which the forms actually found bear to the numbers theoretically probable. 

 If the reasoning is correct, we can expect to find few if any more species than have 

 already been collected in at least five out of the twelve formations so indicated, while 

 of the Pleistocene of North Creek only about one-third of the possible species has been 

 obtained. In a general way I believe these figures to be approximately true. 



In the vast number of species which have been considered during the construction 

 of this table it is improbable that the figures in every case should be mathematically 

 exact, but it is probable that the errors if corrected would not affect the general con- 

 clusions drawn from the table as it stands. In several cases if the numbers were in- 

 creased it is unlikely that the percentages would be materially affected. 



The names given in the table will be familiar to the reader, but it seems worth while 

 to specify that under G the name Chesapeake applies merely to the Floridian Miocene 

 and does not include that of the more northern States. Under Pascagoula our collections 

 include four species. Professor Smith and Mr. Aldrich announce the presence in the 

 clay of ten more, and these have been added, though I have not seen them. 



For the Shiloh list I am mainly dependent on Professor Whitfield's monograph 

 with some additions from my own observations. For the Vicksburg and Jackson lists 



