PllOCEEDINGS OF GEOLOGICAL SOCIETIES. 
197 
tlier the polish ^Yas supposed to be produced by ice itself or by the clay 
beneath movinsf ice, an agency which would seem to him to have been ne- 
cessary. At all events, from the gently undulating character of the coun- 
try, it would seem that the ice did not belong to local glaciers, but more 
probably to a large sheet covering the whole surface of the district. In 
connection with this subject he would mention that his friend Dr. Mel- 
ville, of Galway, had expressed the opinion that in the neighbourhood ot 
that town they had the true " boulder clay " of Scotland, while in the east 
of Ireland the superficial deposit had been subjected to a considerable sift- 
ing action, \\ hich had changed its character. The general opiujon at the 
present day is that this boulder clay is not aqueous'clrift, but consists of 
the debris of rocks ground down on dry land. Not far from Galway he 
had observed a sandy clay full of boulders, so compacted together as to 
form a sort of conglomerate, in parts almost stratified, which had been 
probably formed by the pushing action of the ice slipping from the land 
to tlie sea. 
The Secretary read a paper by W. Harte, Esq., C.E., " On a ISew 
Echinoderm from the Yellow Sandstone of Donegal." The fossil which I 
have the honour to bring under the notice of the Eoyal Geological Society 
of Ireland, and of whicli I request tlieir acceptance for their museum, was 
obtained by me lately in making a road on the western shore of Lough 
Eske, about six miles from Donegal. The specimen is a cast in the yellow 
sandstone, the markings being in an unusually good state of preservation. 
The shape is orbicular — depressed, — the base is wanting, and the cast seems 
to have yielded by pressure and is spread out, somewhat of a bell-mouthed 
shape, though this has been efiected with very little distortion or disar- 
rangement of the plates. The interambulacral spaces are composed at 
tlie lower extremity of the fossil of five rows of plates, and it is probable 
that they exceeded that number at the base. The two rows next the am- 
bulacra are pentagonal except the upper plates, which are nearly trian- 
gular. The other three rows are hexagonal, very irregular, and nearly all 
become obsolete before reaching the ambulacra. These hexagonal plates 
are almost smooth, or at least only marked by very minute tubercles, of 
which, I think, traces can be detected. The genital and side pentagonal 
plates are very difl^erent. The genital plates have each a large perforate 
tubercle, as in Archaocidaris, surrounded by a depressed ring, and this is 
again surrounded by a ring of about sixteen pores. Of the rows next the 
ambulacra the first plate (counting downwards from the apex), which is 
nearly triangular, has a small tubercle. The rest of the plates in this row 
are all pentagonal, and both they and the tubercles increase in size down- 
wards. The second, fourth, and seventh plates have each one large tuber- 
cle, surrounded by a depressed ring, and this again by a circle of very 
small tubercles. The third, fifth, and sixth plates are quite plain. The 
foregoing description applies to all the interambulacral spaces, so that thus 
we have a series of concentric circles in the pentagonal rows at increasing 
distances from the apex down. The ambulacra are large ; the perforations 
are situated in two depressions, and consist of three rows of two each (six 
rows in all) in each ambulacral depression. Three small plates cover each 
space, and there are two perforations in each plate. Four of the ambula- 
cral plates equal in depth one of the side plates. The dividing ridge shows 
the ambulacral plates well, having one small tubercle in each. A detached 
portion of either this same, or of another of these specimens, appears on 
the same stone close to it, showing the plates of the ambulacra very dis- 
tinctly. There are no traces of any spines that I can see in this fossil, un- 
