164 JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
and cannot, therefore, be supposed the result of mere metamorphic 
action induced at a subsequent period. 
Under those circumstances, and in the absence of a better hypo¬ 
thesis, I think the concretionary structures in question may be ra¬ 
tionally regarded as organic remains, in which the specific characters 
have been obliterated, and as probably referable to some genus of 
zoophytes, composed of adhering tubes, of which we have familiar 
examples in Holy sites catenulatus , Favosites Gothlandica , and Litho- 
strotion striatum. 
This conclusion, with respect to the semi-globular masses, is by 
no means invalidated by reference to others of a different kind, for 
these in many cases occur as small compressed cylinders, about two 
inches in length, and of nearly half an inch in diameter, suggesting 
the idea of Encrinite stems, or of broken Orthoceratites; and in one 
particular instance a concretion was found, almost identical with both 
valves of an ordinary Productus. 
Thus, the observed facts, whether taken collectively or in detail, 
would appear all and each to indicate the probable existence of fos¬ 
sils in the limestone of Culdaff; and I have to hope that sufficient 
has been stated to induce further attention on the part of geologists 
to the rocks of the primary series. 
The Society met on the 11th of June, 1856, on which occasion the 
following Papers were read. 
OESERVATIONS ON THE STRUCTURE OF STRATA. BY PATRICK GANLY. 
1. Succession of Laminae. 
On the assumption that loose matter, accumulated by the action of 
water, assumes a chronological arrangement, geologists are enabled 
to establish the relative ages of a series of sedimentary rocks "from 
their order of superposition, which may in general be easily deter¬ 
mined by observation, so long as tHe strata lie level, or at low incli¬ 
nations to the horizon; but becomes a question of considerable diffi¬ 
culty when they stand nearly vertical, or happen to be altogether 
turned over. 
To ascertain the true succession in cases of this kind, will some¬ 
times require a good deal of technical artifice, such as tracing out 
