Algonkian Algce, in Permian of England. 



197 



concretionary limestones. I was fortunate in having as 

 a guide Doctor D. Woolacott, who has studied the district 

 in great detail and published several important papers 

 on its stratigraphy and tectonics. We visited especially 

 the extensive Fulwell quarries, w^liere the concretionary 

 structures are seen in wonderful variation. Here there 

 are concretions of the more ordinary sort, e. g., the 

 ^^ cannon ball" and the ^'botryoidal" types, along with a 

 great display of other more cellular structures, and 



Fig. 3. — Three-fourths nat. size. 

 Walcott. 



Compare with Newlandia frondosa 



among these I recognized at once several types which 

 struck me as being identical with those shown by Walcott 

 in the splendid illustrations accompanying the paper 

 cited. 



The many curious structures of these Permian lime- 

 stones were described in 1835 by Sedgwick,^^ whose very 

 detailed and accurate descriptions give a clear account of 

 the great variety of these stromatolite structures in the 

 Permian limestone of eastern England. His illustrations, 



'A. Sedgwick, Trans. Geol. Soc, London, 2d ser., 3, 37-124. 



