120 TRANSACTIONS OF THE WAGNER FREE 



Fulgur coronatum, Helicina sp. ? 



" spiniger? *Strophia incana ? 



Turbinella polygonata, Venus penita, 



Vasum subcapitellum, * " magnifica, 



Voluta musicina, Cytherea staminea? 



" (Lyria) zebra. " Sayana? 



Mitra (Conomitra) angulata, nuciformis, 



Conus planiceps, *Chama macrophylla ? 



*Pleurotoma ostrearum, Lucina Hillsboroensis, 



Cypraea tumulus, Crassatella deformis, 



Oniscia Domingensis, Carditamera serricosta, 



Natica amphora, *Arca imbricata, 



" streptostoma, * " Listeri, 

 Amaura Guppyi, " arcula, 



Turritella pagodaeformis, Leda flexuosa, 



Tampae, *Lithodomus inflatus? 



Turbo crenorugatus, *Lima scabra. 



The species preceded by an asterisk are living forms. 



Of the forty-seven species here enumerated from four to eight are 

 living forms, so that the representation of the recent fauna might perhaps 

 in a general way be assumed to be about 13-15 per cent. The Miocene 

 age of the deposit is thus placed beyond question ; and if the proportion 

 of living forms determined for this limited collection be assumed to be 

 approximately correct for a more extended series, then manifestly the 

 exact position of the horizon will be not far from the base of the Miocene. 

 This accords well with the location of the formation, and its own special 

 faunal relationship. None of the fossils possibly, with one exception 

 appear to be identical with forms found in the Oligocene deposits of the 

 southern United States ; on the other hand, some six or more Oniscia 

 Domingensis, Amaura Guppyi, Venus niagnifica, fCliama tnacropliylla, Area 

 imbricata, fArca Listeri, Lithodomus, sp. ? are common to the deposits of 

 Santo Domingo. In these deposits the proportion of recent to extinct forms 

 is claimed by Gabb to be as high as3Oto33percent.("Topographyand Ge- 

 ology of Santo Domingo," Trans. Am. Philos. Soc., xv, p. 101), which would 

 make the formation of considerably newer date than is indicated by the 

 Florida fossils. I have not had an opportunity to verify Mr. Gabb's determi- 

 nation, but from a casual examination of his collection it appears to me that 

 strong exceptions might be taken to many of the specific determinations. 

 Comparisons with a number of forms satisfy me that in at least several 

 cases the selected distinctive characters cannot be relied upon, being more 

 imaginary than real, and this criticism applies as well to cases of specific 

 identification as to those of specific separation. But with all necessary 



