384 



GEOLOGY OF THE SECOND DISTRICT. 



It is taken from a specimen which is apparently charred or carbonized, and shows a tendency 

 to a fibrous structure in the interior. 



In tlie preceding figures, the organic structure is destroyed ; and as it usually occurs, it is 

 impossible to determine its nature. An imperfect fibrous structure, it is true, is brought out 

 by weathering, but nothing appears sufficiently decisive to determine whether it belongs to 

 the animal or vegetable kingdom. From the appearance and characters of species as usually 

 found, it resembles a vegetable more than an animal ; and hence Mr. Conrad, in describing 

 it, placed it among the marine plants, in the order Fucoides. 



Forttuiately, on examining this rock in the valley of the Mohawk, in the vicinity of Fort- 

 Plain, I discovered several specimens which clearly revealed the character of this fossil ; and 

 from these observations, it appears to belong to the family Polyparia. Upon the outside of 

 the branches there is a thin covering, spreading apparently over the whole animal, which is 

 perforated by pentagonal cells or pores, which communicate with thin longitudinal spaces or 

 compartments. When the rock is weathered, if the surface is parallel to the length of an 

 individual branch, it is partially fibrous ; but if transverse, the surface is set with cruciform 

 figures, as in the following cut : 



96. 







m'A 





Nos. 1 and 2 are representations of a surface which has been weathered transversely, so as 

 to expose sections of the branches ; and No. 3, is a representation of the outside, showing the 

 pentagonal cells. 



It appears from an examination of this subject, that since this fossil is enclosed in a very 

 compact rock, which breaks always with a conchoidal fracture, it is impossible that it can be 

 developed by breaking ; and hence the only process which can develop it, is the natural 

 weathering of the rock. But the external surface of the fossil is so thin, and the cells so 

 fragile, that in most cases the whole organic structure, which alone can indicate the kingdom 

 to which it belongs, is worn entirely off, or breaks down as the process proceeds, without 



