419 
fish fauna of the lower coal measures of the halifax 
and littleborough districts, 
by edgar d. wellburn, l.r.c.p. 
Plates LXI. and LXII. 
{Read X-ovemht^r 11 th, 1S98.) 
[ntroduction. 
My reasons for considering the " Fish Fauna " of these two 
districts together is that it may be taken for granted that the 
Yorkshire and Lancasliire coal fields were joined and continuous 
until they became separated at the close of the Carboniferous 
period by the upheaval which caused the Pennine anticline. 
7%e Halifr.r. Coal strata forms a compact group of rocks, 
consisting of beds of shale, sandstone, rag, bind, seat-earth, 
gannister, ironstone, and fossiliferous beds of marine and fresh 
water origin, the whole forming that portion of the Lower Coal 
Measures which is enclosed between the Rough Rock at the 
base and the Northowram and Elland flagrock at the crown. 
The conditions nttending the formation of the different beds 
were of a very varied character, the area being sometimes a land 
surface at others a great estuary, inhabited by mollusca and 
fishes, and into which the sea occasionally erupted, bringing 
marine shells and fishes. 
I have found the majority of the fish-remains in a very 
thin layer of shale lying direct! ij on the Hard Bed Coal. 
Immediately above this point there is a bed of Marine Shells 
(Aviculo-pectens, l^^c), from 3 inches to 6 inches in thickness, 
and overlying this '• pecten bed " the shale contains a large 
number of nodular concretions, locally known as " Baum Pots," 
which are composed of the carbonates of iron and lime and are 
of great interest, as they sometimes contain fish-remains as well 
as Goniatites, Nautili, <i;c. ; the fine type specimen of Cadacanthus 
Phillipsi Agassiz having been found in one, and another contained 
a fine specimen of Acrolepis Hopkinsi McCoy. 
