420 



PROCEEDINGS OF THE ACADEMY OF 



[1898. 



In the lists above there are but 3 species occurring injboth locali- 

 ties, viz. : Cyiherea convexa, Liicina crenulata, and Ostrea virginica. 

 Adding the numbers in the two lists and deducting these three, 

 since they have been counted twice, we find there are, altogether, 52 

 molluscan forms, of which 3 are not specifically identified. Analyz- 

 ing the remaining 49, we find their numbers range in geological 

 time as follows : — 



fr ich it will be seen that there are 



.iocene and pre-Pliocene forms 7 species. 



Ranging from Miocene to Recent 16 species. 



Both Pliocene and Recent 14 species. 



Recent, including Pleistocene 12 species. 



Judging from these proportionate figures alone, which show 42 

 forms still living, out of a total of 49, the writer would be inclined 

 to assign the age of the beds from which these fossils were obtained 

 as not earlier than late Pliocene time, while it may even possibly 

 belong to Pleistocene time. 



We may, however, more particularly note other reasons for this 

 conclusion as to age. 



Twenty-six, or fully one-half of the shells specifically identified, 

 clearly have a post-Miocene aspect, including two forms, Fulgur 

 carica and Ostrea virginica, which are the most numerous of the col- 

 lection. The specimens of F. carica present a peculiarity of sculpt- 

 ure which distinguishes them from the shells now living upon the 

 coast; the surface being densely scored by fine crimped or undulat- 

 ing spiral stria?, in fully adult, large individuals. In recent shells 

 of similar size such striation is nearly obsolete or wholly wanting, 

 even when the superficial coat has not been removed by erosion. 



