wi the Carboniferous Limestone of Clifton. 487 



vonian beds, through the lower shales, massive beds, and upper 

 shales of the Carboniferous series into the Millstone-grit. 



As far as the author can ascertain, the fossil contents of the 

 beds in question have never before been noticed. 



The beds also, with the succeeding ones, cannot be identified 

 with those enumerated in Mr. WilUams's section as published 

 by the Government Surve5^ They most probably ought to be 

 placed between those numbered 419 and 430 ; but Mr.\yilliams's 

 measurements differ so materially, that neither can be identical 

 with the microzoal bed, which, for the sake of convenience, the 

 author has named the " Bryozoa-bed.^' This discrepancy has 

 very likely arisen from Mr. Williams having taken his section 

 through some other part of the range, where the beds have 

 thinned out. 



The Bryozoa-bed is a well-marked red crystalline bed of lime- 

 stone, and very ferruginous. It reaches 12 feet in thickness, 

 and dips to the S.S.E. at an angle of about 60°. 



The Bryozoa-bed is undoubtedly one deposit, because not the 

 least bedding is observable, nothing more than the usual cleavage- 

 joints of the limestone being visible. Another fact is that a piece 

 taken from any part of the bed will exhibit the same kind and 

 number of fossils, which is not the case with the two under- 

 lying beds, one 2 feet four inches and the other 2 feet 9 inches 

 in thickness. Although the two latter have to the eye exactly 

 the same appearance as the Bryozoa-bed, yet they are both 

 unfossiliferous, or nearly so. 



The absence of alumina in these beds is very remarkable, be- 

 cause the Lower Limestone shales are very argillaceous. 



The fossils are casts, or else pseudomorphs, composed of per- 

 oxide of iron and silica. They are very brittle and porous, and 

 insoluble in cold nitric and hydrochloric acids. About one-third 

 consists of the most exquisite casts of infundibulate Bryozoa, 

 showing the cells and their details in the most beautiful manner. 

 The greater part of the remaining fossils are those of Encrinital 

 ossicula, which generally are found detached from the column. 

 When these are examined under a power of 60 diameters, their 

 surface appears to be porous, the pores being arranged in a 

 radiate order. Sometimes, though rarely, the ossicula occur 

 attached to the central axis. Very few pelvic plates are met 

 with, and those correspond to the genus Poteriocrinus. Besides 

 the above, moulds quite as perfect of Entomostraca and Gastero- 

 poda are present. 



The Bryozoa-bed is situated at the base of the Lower Shales, 

 about 100 feet above the termination of the Old Red series. 



The immense mass of fossil remains in this bed is almost in- 

 credible. Taken from any part, they constitute, at the very 



