ON IRISH PERMIAN FOSSILS. 
79 
For present purposes it is unnecessary for me to refer to any 
but the first and third members. Both are distinguished from each 
other by palaeontological differences. The first member is charac¬ 
terized in the north of England only by a few species of fossils, such as 
Mytilus squamosus, M. septifer , Leda Vinti , Pleurophorus costatus, Schi- 
zodus Schlotheimi, Cythere inornata; whereas the third contains about 
143 species (including most of those just named), many of which are 
bryozoic corals and palliobranchiate shells. The first member is 
extensively developed on the coast of Durham, the shore cliffs be¬ 
tween Hartlepool and South Shields being principally composed of 
it. In some localities it is highly crystalline, varying extremely in 
structure; but in most places it is earthy, oolitic, cellular or compact, 
of a yellowish or brownish colour, and highly charged with carbo¬ 
nate of magnesia. The late Professor A. Johnstone has published the 
following analysis of the oolitic variety, which is very abundant 
around Hartlepool:— 
Carbonate of lime,.54*5. 
Carbonate of magnesia,. 44*93. 
Alumina, iron, and phosphoric acid, . . 0*33. 
Insoluble matter,.0*24. 
I have given this analysis of the magnesian limestone of Cultra, 
because it closely corresponds with one published by Sir Robert 
Kane.* Mr. M‘Adam has kindly furnished me with another of the 
Tullyconnel limestone made by Dr. Hodges, of Queen’s College, Bel¬ 
fast, showing that it too has a very similar chemical composition. 
Thus, in its lithological and chemical characters, the first member, 
as it occurs in Durham, offers a remarkably close agreement with 
the Tullyconnel and Cultra magnesian limestones: further, both pos¬ 
sess a palaeontological resemblance, which is equally remarkable; 
for in the Tullyconnel and Cultra beds there is very nearly the 
same assemblage of fossils as occurs in the upper Permians on the 
coast of Durham.f This being the case, I cannot refrain from 
* Industrial Resources of Ireland, page 246. 
f Mr. Bryce states in his “ Geological Notice on the Environs of Belfast,” &c., 
that Terebratulse and Products occur in the Cultra magnesian limestone. There is, 
probably, an error in this statement, as I certainly saw none of these fossils in Mr. 
M‘Adam’s collection; nor is Mr. M‘Adam himself acquainted with any; nor are 
there any noticed in Dr. Griffith’s list. 
Vol. VII. 
I 
