W. H. Hudleston — Creechharrow in Purheck. 



199 



to the larger ones previously described as th( 

 structure is entirely concentric, and this is 

 pisolites as well as in the circular ones. 

 are seen to be compound, with a very irre^ 

 two or more foci of crystallization, and in 

 figures result. 



> horseshoe form. The 

 shown in the flattened 



Some of these bodies 

 ;ular periphery, having 



this way very curious 



^ 



\ 



\ 



4a 



Fig. 4. — Fragment of the hard pisolitic limestone showing two faces cut at right 

 angles to each other and polished. | x 1|. 



Fig. 4fl!. — Section of one of the pisolites, drawn as a transparency, x 6. 



The magnified section of one of the quadrate pisolites (Fig. 4a) 

 displays some features which are not seen in all the specimens. 

 For instance, there are two lacunas of clear calcite, which partly 

 separate the regular annular system of brown calcite from the 

 ordinary matrix. This is probably due to partial solution of the 

 matrix subsequent to the formation of the pisolitic concretion We 



