INSTITUTE OF SCIENCE, PHILADELPHIA. 27 



A tough sand-rock, of undoubtedly recent formation, crops out at 

 Fort Myers, just above the landing; as far as I could determine, it was 

 destitute of organic remains, or when present these were in such a frag- 

 mentary condition as to be unrecognizable. I was also shown along the 

 river's bank a number of large nodules or boulders of a fossiliferous 

 limestone, which were reported to have been obtained from a neighbor- 

 ing well-digging. In these the recent Venus cancellata was clearly deter- 

 minable ; from the very great abundance of this shell, its excellent state 

 of preservation, and the general appearance of the imbedding matrix, I 

 feel satisfied that the rock is of Post-Pliocene age certainly not older 

 than late Pliocene. A somewhat similar rock, densely charged with the 

 same species of mollusk, and with various other bivalves, besides a host 

 of gasteropods (Fulgur, Turbinella, etc.) crops out in a field on the left 

 bank of the river, about 20 miles by water above Fort Myers (six or 

 seven miles in a direct line?), not very much beyond Telegraph Creek 

 crossing. The species of mollusk recognized here were: Venus cancel- 

 lata, Venus mercenaria (pcnnagna?*), Cardita Fluridana, Area transvcrsa, 

 Fulgur sp. ?, etc., all of them apparently still living in our waters, from 

 which it is to be inferred that the deposit is of Post-Pliocene age. The 

 rock is overlaid by a sandstone, in appearance identical with that which 

 crops out at Fort Myers, of which it is the probable equivalent. Imme- 

 diately below the fossiliferous stratum first described a tough rock, largely 

 charged with shell-fragments, and containing numerous impressions of 

 bivalves, mainly of small size, makes its appearance at water-level, below 

 which it extends for probably several feet. The very unsatisfactory con- 

 dition of the embedded remains, rendering a positive determination of 

 species impossible, precluded also an absolute determination of the horizon. 

 The sharp line of demarkation separating this deposit from that immedi- 

 ately overlying it, coupled with the knowledge that extensive Pliocene 

 deposits are developed in the further course of the stream, leads me to 

 suspect that this basal rock is also Pliocene, or, at any rate, that it repre- 

 sents a geological period distinct from that which is indicated by the 

 Venus cancellata bed. 



Just below Thorpe's, and in both banks, a white shell marl rises out 

 of the water to a height of about two and a half or three feet. It con- 

 tains great quantities of a ponderous flat oyster (Ostrca meridionalis), dis- 

 tinct from any of the related forms now living, and of two large scallops 

 Pcctcn comparilis, and a form, P. solarioidcs, resembling it in general out- 

 line, but differing in its much greater size, and in several other peculiari- 

 ties of structure. Both the oyster and the scallops could be detected in 

 the marl-rock some distance beneath the surface of the water, whence 

 several specimens were obtained by means of the mattock. The Ostrea 

 Virginica is also very abundant in the sand rock. On top of this fossil- 



