PROCEEDINGS OF GEOLOGICAL SOCIETIES. 



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ther the polish was supposed to be produced by ice itself or by the clay 

 beneath moving 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, which had changed its character. The general opinion at the 

 present day is that this boulder clay is not aqueous drift, 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 the sea. 



The Secretary read a paper by W. Harte, Esq., C.E., " On a New 

 Echinoderm from the Yellow Sandstone of Donegal." The fossil which I 

 have the honour to bring under the notice of the E-oyal Geological Society 

 of Ireland, and of which I request their 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 effected with very little distortion or disar- 

 rangement of the plates. The interambulacral spaces are composed at 

 the 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 different. The genital plates have each a large perforate 

 tubercle, as in Archgeocidaris, 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 sec in this fossil, un- 



