290 



Dr. John T* Plummer on the 



Vast numbers of the shells of this formation are unbroken ; 

 and many retain all the sharpness of outline, and the delicate 

 markings of a recent shell. The hinge and the interior of the 

 shell are often found in a state of fine preservation ; these parts 

 being exposed by the separation of the valves, anterior to the 

 process of petrifaction taking place in them. Most of our fossils 

 are therefore easily characterized. Being constantly and very 

 easily detached from the rock by the common agencies of time, 

 bushels of them can be readily collected in the course of a day. 

 So far as I have witnessed, all the fossils of this deposit are cal- 

 careous, in which they differ from those of the formation imme- 

 diately above it. 



Persevering research has enabled me to collect upwards of 

 forty different species of organic remains from the rocks in this 

 vicinity. I greatly regret that I cannot furnish a perfect cata- 

 logue of these species ; my means for gaining paleontologicai 

 information are very limited ; but conceiving that at least a pit- 

 tance of information may be gleaned from it, I offer you the fol- 

 lowing incomplete enumeration : 



Alga. — If paleontologists are correct in assigning the fucoides 

 to the vegetable world, we have, I think, four species of this 

 sea-weed ; and it is a remarkable fact, that the surfaces of the 

 layers presenting them are nearly smooth, more or less laminated, 



Fig. 4. 









surfaces 



and entirely free from other fossils ; while the 



other strata are generally very much roughened 



tially imbedded shells. These fucoidal surfaces are considerably 



par- 



