276 ]\JE. E. WEXHERED OX THE OCCURRENCE OP 



Following the Inferior Oolite in ascending- order, we pass from the 

 Lower Freestones into the Oolite-marl, and above that we come to 

 the Upper Freestones. What I have said with regard to the crys- 

 talline condition of the Lower Freestones also applies to the Upper 

 Freestones, when taken as a whole ; but a striking exception has 

 been found to this in freshly exposed beds of this freestone near 

 Chedworth, about eight miles from Cheltenham. In these beds 

 there are patches of oolite, of blue tint, which is due to the iron in 

 the rock being in the state of carbonate, the original condition in 

 which it existed after the formation of the rock. In the yellow 

 oolite the iron has been converted into ferric oxide. Where the 

 original carbonate of iron has not been converted into the ferric 

 condition tlie oolite-spherules show their original structure better 

 than is the case where the iron has been converted into ferric oxide, 

 and in this the Girvanella-tubuli are clearly made out. The tubes 

 show a somewhat dark exterior ; and, when cut in section, the in- 

 terior is seen to be filled with crystalline calcite or dark argillaceous 

 material. They are smaller than G. pisolitka as it occurs in the 

 Pea-Grit spherules, but otherwise similar ; and I therefore regard 

 them as a variety of that si)ecies. In PI. XL fig. 4 I have represented 

 a spherule in which tubes are clearly distinguished ; but in parts 

 the outlines have been obliterated by mineral changes, and we then 

 get the identical structure which is characteristic of most of the 

 oolitic spherules in the Upper Freestones. There are others which 

 show a regular crystalline concentric arrangement, and they may 

 possibly be of concretionary origin ; but I am disposed to regard 

 them as spherules in which the Girvanella-txxhes have become crys- 

 talline and the outlines consequently obliterated. 



Another form of Girvanella has also been met with in the Upper 

 Freestones. It consists of a dense mass of tubes, measuring -01 

 millim. in diameter, which form a crust attached to foreign objects 

 (fig. 5). It is very similar to the Carboniferous G. incrustans, and 

 might perhaps be regarded as identical with that species. For 

 reasons to be explained under the head of " new species," I think it 

 best to regard it as a variety, with the name of G. incrustans, 

 variety Liicii, after W. C. Lucy, Esq., the excellent President of the 

 CottesVold Naturalists' Field Club. 



I now pass to the upper divisions of the Inferior Oolite. In the 

 new railway now in course of construction between Cheltenham and 

 Cirencester some fine exposures of the Cli/peus-Plottii beds are seen. 

 In these there are large oolitic spherules which measure as much as 

 4 millim. in diameter, though the average size may be stated at 

 about half that. In most of these there is no structure except the 

 dark granular and occasional streaks and circles of calcite, but in 

 others the Girvanelf a-tubiiles are seen. I have therefore no doubt 

 that the spherules in this division of the Inferior Oolite are not 

 concretions, but due to a variety of Girvanella pisolitica. 



