64 REPORT—1857. 
with about twenty alternating pinnules, which are apparently covered by theca, or 
cases of the reproductive germs, presenting an appearance somewhat resembling rows 
of small flowers. The unique character of this singular plant, possessing, as it doés, a 
form so totally unlike any recent or fossil plant, combined with the rave circumstance 
in fossil ferns of the carboniferous period, that of bearing organs of fructification, which 
here appear to be so fully developed, renders it of great interest, and may possibly 
constitute it a new generic form. 
On the Drift of West Galway and the Eastern parts of Mayo. 
By J. Birmincuam, of Millbrook, County Galway. 
The author sets out by alluding to the interest and importance of the Irish driftsi 
general, which are well developed in the district to which his paper refers, ‘They differ 
from the drifts of many other countries by containing no fossiliferous evidence of their 
comparative date: and, to account for the absence of shells or any traces of boring 
molluscs in their materials, the author suggests that the remains of those great drifts, 
which are now exposed, never formed the surface of the former sea-bottom, but were 
probably situated at a depth to which no shell-fish ever reached, He divides the 
drift of his district into three principal divisions; namely,— 
1, The Clay Drift, from a point between the south-east and the west, forming cliffs 
on the north, east, and south shores of Galway Bay. 
2, The Great Boulder Drift, from a point between the north and the west, over= 
lying the former. 
3. The Escar Drift, forming the chains of gravel hills in the interior of the country, 
from the south-west. 
The direction and sequence of those drifts are inferred from their mineralogical 
characters and relative positions. The perfect round forms of the Escar Hills, and 
the complete curves that their beds or layers generally exhibit in any stratified sec- 
tion, not only prove their subsequency to the other drifts, but show that their emer- 
gence from the waves, at which time they must have received their present contour, 
did not take place during any glacial period; for if icebergs had been moving about, 
and grooving the rock bottom of the shallowing sea, the Escars would scarcely have 
escaped their action, which would be recognized in the tabulation of their summits, 
or other significant appearances, The long ranges of those gravel hills may show the 
resultants of currents that had been subdivided from the main stream, and met again 
at large angles beyond the limits of opposing hills. 
He refers to a fact which he considers worthy of note, from being at variance, as he 
believes it to be, with recognized theory. He often observed that in the Esear drift, 
the coarser gravel and boulders betray a tendency to arrange themselves in the upper 
parts of the mass; and he has remarked the same phenomenon in the shoal. beds 
periodically formed by river floods. 
He maintains that it is to the power of moving water, and not either to land glaciers 
or floating ice, that the great boulder drift of his district is also to be attributed. The 
fact of large boulders being found on the sides and summits of hills, which they must 
have ascended, sufficiently refutes the land-ice hypothesis ; and the floating-ice theory 
is rendered improbable by the appearance of a regular increase in number, as well as 
in size and angularity, of the erratic blocks as they are followed towards their source. 
Their decrease in number, according to their remoteness from their parent rocks, 
might, indeed, be accounted for on glacial principles, but not so easily their decrease — 
in size; for though the ice-raft may waste away by degrees, and its powers of buoy- 
ancy become less, still this must be thought to affect the total quantity, rather than 
the individual parts of the load that it bears, As its cliffs succumb in its progress 
through the warm sea-waves, its burden may gradually be reduced ; but there is no 
reason why the largest masses should not be found among the mixed materials which 
are still carried on its contracting area. If ice, therefore, were the transporting cause 
of this drift, we should expect to see, scattered over the land, even a few large boulders 
derived from distant localities; but those are never found so situated; they must be — 
looked for near their source. The clay drift is in some places stratified, and in others 
amorphous; and it presents no phenomena which, in the author's opinion, oblige us 
to have recourse to the agency of ice to account for its formation, while its southerly 
ds 
