84 . Reports and Proceedings : 
levissimus, Psammodus porosus, and Coprolites. Under the above- 
mentioned soft marl come three beds of red crystalline limestone, 
exactly similar to each other in lithological character; but the upper 
and lower are unfossiliferous, while the middle bed is one of the 
most extraordinary assemblages of fossils perhaps ever seen. It 
is 85 feet thick, dipping SSE. at an angle of 68°, and is probably 
that mentioned in Mr. Williams’s seetion as No. 420. This must 
have been one long-continued deposit, from its great thickness, and 
from the fact of not the least ‘bedding’ being visible, only the 
usual joints of the limestone. A very singular circumstance is, that 
a piece broken off from any portion of the bed exhibits the same 
number of fossils, all small, ranging in size from 1-100th to 1-20th 
inch in diameter. The only fossils of a larger size yet found are a 
single specimen of Spirifera, a small tooth (Psammodus porosus), 
and a small Spine. The absence of alumina is very remarkable; 
because so great a quantity is usually present in the Lower Lime- 
stone Shales above and below this bed. The fossils are casts, or 
rather pseudomorphs, composed of a peculiar combination of 
peroxide of iron and silica; they are very brittle, porous, and in- 
soluble in cold nitric and hydrochloric acids. The calcareous cement 
being perfectly soluble in these acids, the fossils are easily obtainable. 
About one-third consist of the most exquisite casts of Infundibulate 
Bryozoa, showing the cells and other details in a very beautiful 
manner; a great part of the remainder are casts of Encrinital 
Ossicula, with a few pelvic plates corresponding to those of the genus 
Potertocrinus. Numerous casts of two species of Entomostraca also 
occur, which show the hinge-structure very distinctly. The im- 
mense mass of fossils in this bed is almost incredible ; taken from 
any part, they form at the very lowest estimate 20 per cent. by 
weight of the entire rock. From an avoirdupois-pound were ob- 
tained 1,600,000 specimens, besides a large quantity of broken shells 
and other débris. It was probably not a bed deposited in the usual 
manner, but rather a bank in the Carboniferous sea, exposed to the 
gentle action of littoral waves. Analogous cases may be seen now 
going on ;—for example, on the coast of Sussex (near Selsea), and 
on the west side of Caldy Island, a deposit may be seen collecting, 
the similarity of which to that under notice is very striking. After 
comparing the Lower Carboniferous Shales of Clifton with the 
descriptions of corresponding beds in Ireland, by Portlock, Jukes, 
and Salter, and with some of the Devonshire strata, Mr. Stoddart has 
no doubt of the geological identity of the Moyola, Altagowan, 
Coomhola, and Marwood groups, and of their agreement with these 
Lower Shales of Clifton. It is true that none of the larger Brachio- 
poda occur in these beds of the Clifton Shales, but they are likewise 
wanting in the Irish beds, where the thickness diminishes as towards 
the North of Derry. Here the Clifton and Irish fossil fauna very 
nearly agree. On the other hand, where the Lower Shales in Ireland 
attain a very great thickness, fossils are found identical with those of 
the Marwood group. This will be rendered mere evident by an 
examination of the accompanying table :— 
