56 Pelecypods of the Bowden Fauna [254 



Duplin or later forms,, this relation is emphasized by the 

 initial appearance of the section Pleurolucina of the genus 

 Phacoides. Although the section Eulopia of Myrtaea has 

 been reported from the Tampa fauna, it reaches its earliest 

 development of any importance in the Bowden fauna and is 

 not present in any of the post-Tampa Florida deposits. A 

 peculiar Hare represents a type that has not been recognized 

 except in the Eecent seas and typical Bellucinas have not been 

 reported from horizons lower than the Duplin. The super- 

 family under discussion includes a Eecent Divaricella and also 

 a Recent Diplodonta, which is unknown from any intervening 

 horizon. Two Eecent Cardiums, a Fragum and a Laevi- 

 cardium, are confined to Miocene and later horizons on the 

 mainland,, and Trachycardium includes a type unknown from 

 beds earlier than Pliocene. The Yeneridae supply a quota of 

 later Tertiary elements. The Bowden Tivela is the only rep- 

 resentative of the genus recorded from American Tertiary 

 deposits and a Recent species of Gafrarium (Gouldia)}ias not 

 been recognized at any other Tertiary horizon. The single 

 Cyclinella is very close to a Recent species and the most abund- 

 ant Chione s. s. is allied to a Duplin form. The genus Paras- 

 tarte, unrecorded from a pre-Miocene horizon, is represented 

 by a species scarcely distinguishable from the Miocene to 

 Recent type of the genus. Among the Tellinacea are to be 

 noted a Recent Strigilla, a Semele that is surprisingly close to 

 a Pliocene and Recent form and the initial appearance of the 

 subgenus Cymatoica of the genus Macoma. 



Though many of the post-Chipolan elements are found 

 among the characteristically tropical groups, yet the introduc- 

 tion of super-specific groups, some of which are not exclu- 

 sively tropical, can hardly be disregarded. The Bowden pele- 

 cypods are distinctly younger than those of the Alum Bluff 

 faunas, as those faunas are now known. It may be suggested 

 that the Bowden fauna is Burdigalian, that is, Lower Miocene 

 in the sense of most American stratigraphers. 



