INSTITUTE OF SCIENCE, PHILADELPHIA. 



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in almost countless numbers, and attract attention, apart from their pro- 

 digious development, by their great variety, large size, and beautiful state 

 of preservation. The whole bank much resembles a fossil shell-beach, 

 and recalled to my mind the wall of shells extending from Little Sarasota 

 Inlet to Casey's Pass. But that this was not its true character is proved 

 by the perfection in which individual shells had retained their outlines 

 even the most delicate, such as Pyrula (Ficula), showing little or no surf 

 action and by the great number of forms (Panoprcas, Areas) which still 

 remained in their normal positions, both valves firmly attached the same 

 as they originally occupied when living. 



The number of recent forms occurring here is very great, so that at 

 first glance I scarcely doubted that the formation was of Post-Pliocene 

 age, a conclusion to which I was further led by the absolute freshness of 

 many of the specimens. Closer inspection, however, revealed a host of 

 forms which had no analogues in the recent fauna, and others, again, 

 which, while closely approximating living species so much so, indeed, as 

 to leave no doubt as to their inter-relationship yet differed sufficiently 

 to indicate a long period of time during which the modifications, resulting 

 in the distinctive characters of the recent species, were brought about. 

 This relationship between the old and the new fauna is very remarkable, 

 and perhaps nowhere else does the doctrine of transformisin or evolu- 

 tion receive stronger support from invertebrate paleontology than here. 

 The lines of derivation through which some of the modern forms have 

 passed are perhaps best seen in the case of one or two species of Area, 

 which stand in unmistakable proximity to the recent A. incongrtta and 

 A. Floridana, in a large volute as ancestral type of the comparatively 

 rare Valuta Jiinonia, and in a ponderous stromb, which strongly fore- 

 shadows the recent Stromlms accipitrinns. Other cases of relationship 

 and obvious derivation might here be cited, but these will be specially 

 noticed in the descriptions of species. 



It is a singular fact that scarcely any of the distinctively Miocene 

 fossils of the Atlantic coast are found here ; such of the Miocene species 

 as do occur are with few exceptions forms that still live along the coast. 

 Per contra, the new species are as a rule strikingly distinct, even in their 

 broadest characters, from the members of our hitherto ascribed Tertiary 

 faunas, or from the equivalent faunas of the West Indian Islands. It is 

 difficult to conceive of the radical difference existing between this fauna 

 and that which ought to be most nearly related to it, whether the special 

 comparison be made with the faunas occurring on this side of the Atlantic 

 or the other. 



The following enumeration of species exhibits the relation existing 

 between the forms now described for the first time and those that had 

 been previously described, fossil and recent : 



