2 THE BRACHlOrODA. 



zone are hardish stone, generally lightish yellow, with plenty of 

 iron grains, so that the term Marls would be rather inappropriate. 

 Besides which, the Humphriesianum zone is often so poorly 

 defined, being sometimes only about six inches thick, that it 

 would seem very peculiar to make such a marked division there. 



In his paper in 1877 Mr. Davidson enumerated 29 species for 

 these beds in this district, one of which, Wold, ornithocephala, 

 leally occurs in the Fullers Earth, and was, by mistake, put 

 dojvn for these beds, and another, Rhynth. Stephen**, is merely 

 the yoang of Rhynch. cynoccphala. Therefore 27 spocies were 

 really shown to exist in the Inferior Oolite of this district. 



In this paper I give a table of zones in which the various 

 species occur in this district, and, as far as I am able, tables for 

 comparison shewing the zones for which the same fossils have 

 been quoted in Gloucestershire, France, and South- West Germany, 

 and I give a table oi localities at which the various species occur. 

 Both these tables have been compiled solely from my own observa- 

 tions in the quarries themselves. It will be seen that I have 

 divided the Inferior Oolite into a large number of zones, but I 

 consider that these divisions, though often small, are well marked, 

 and also that they are a help very much, both in the determina- 

 tion of the various species and also to geologists who explore 

 this district. 



At the end of this paper I give a list of some doubtful species 

 which we have not material enough to determine quite accurately, 

 but I think that the mention of them may induce further search 

 after them. 



An analysis of the various tables of zones given will shew that 

 taken as a whole the agreement is very good. Every now and 

 then, however, discrepancies occur. Such discrepancies may 

 arise from, perhaps, a different fossil being intended in the two 

 cases, or, perhaps, from a not quite accurate determination of the 

 beds, or also from some forms being put into one species by one 

 author which are not admitted by the other. At the end of each 

 species I give a few localities for this district (all the other 

 localities, as well as the zones, may be seen by referring to the 



