1849.] 



EINNEY S REMARKS ON SIGILLARIA. 



19 



posing tlie sides, so as to allow a mould to be made, which has been 

 subsequently filled with soft mud, now forming the ironstone, from 

 above. But if the roots were lying level, on their decomposition, the 

 pressure of the mud and vegetable matter placed over them, being 

 much greater than in the first instance, would press down the moulds 

 and flatten them. Effects similar to those above described have 

 taken place in the specimens both round and flattened found lying in 

 the King coal. 



The vascular axes of Stigmarise vary much in their size, and do not 

 appear to increase in propor- 



tion to the diameter of the 

 root, for they are often larger in 

 small specimens than in those 

 of greater dimensions. Fig. 1 * 

 represents the natural size of a 

 Stigmaria in pyrites in my pos- 

 session, about 1| inch in dia- 

 meter, having its vascular tissue 

 ^gths of an inch in breadth, 

 whilst in fig. 2, the specimen 

 from the King coal, this axis 

 is only a little more than yV^h 

 of an inch, although the dia- 

 meter of the root was about 2| 

 inches. 



Fig. L 



Fig. 2. 



* This specimen I procured from Mr. W. C. Williamson, of Manchester, in ex- 

 change for another. It was found, I believe, in the neighbourhood of Ashton- 

 under-Lyne. 



c 2 



