1871.] cmEEi^ — DONEGAL. 449 



DiSCTJSSION. 



Mr. Seeley remarked, as to the compressed spheroids found in so 

 many rocks, that there was a difficulty in accepting the view of 

 their originating in fluid vesicles, though he was unable to suggest 

 any other theory by which to account for them. He observed that 

 the eggs from the Stonesfield Slate closely resemble those of some 

 birds in the pitting of the egg-shell, which differed from the pitting 

 on such reptile- eggs as he had examined — and that it was of the 

 highest interest to find such eggs in strata containing so many re- 

 mains of ornithosaurian forms, such as Rhamplwrliynchiis and Ptero- 

 dactylus, of which latter genus these were probably the eggs. 



Prof. Rupert Jokes fully recogni^ied the ingenious explanation 

 of the bubble-formed limited slickensides that looked so much like 

 possible fossil fruits, and Mr. Carruthers's masterly treatment of the 

 other specimens ; but he wished that the author would take up the 

 subject exhaustively, and define the nature of other supposed vege- 

 table fossils, such as the so-caUed fucoids, Palceochorda, Palceophyton, 

 Oldhamia, &c., many, if not all, of which Prof. Jones thought to be 

 due to galleries and other tracks made by Crustaceans. 



Prof. Ramsay had known many instances of such blunders as 

 those pointed out, made, not by experienced geologists, but by 

 those unacquainted with the science. Though he had never regarded 

 the flattened spheroids as fossils, he was unable to account for their 

 presence in the clay-beds of different ages. 



Mr, HxJLKE inquired whether Mr. Carruthers regarded the limited 

 slickensides common in the Kimmeridge shales as due to gaseous 

 origin. He remarked on the rarity of PterodactyKan remains as 

 compared with those of other Saurians in the A^'^ealden beds, in 

 which the presumed eggs of Pterodactyle were found. 



Mr. Seeley did not regard the Wealden e^^ as that of a Ptero- 

 dactyle. 



Mr. CAPvKirTHERS, in reply, remarked that the local slickensides 

 mentioned by Mr. Hulke differed in character from those to which 

 he had referred. 



2. Notes on tlie Geology of pakt of the County of Donegal. 



By A. H. Gkeen, Esq., F.G.S. 



[Abstract.] 



In this paper the author described the geological structure of the 

 country in the neighbourhood of the Errigal Moimtaiu, with the 

 view of demonstrating the occurrence in this district of an inter- 

 stratification with mica-schist of beds of rock which can hardly be 

 distinguished from granite, the very gTadual passage from alterna- 

 tions of granitic gneiss and mica-schist into granite alone, and the 

 marked traces of bedding and other signs of stratification that appear 

 in the granite, to which the author ascribed a metamorphic origin. 

 He also noticed the marks of ice-action observed by him in this region, 

 and referred especially to some remarkable fluted bosses of quartzite, 

 and to the formation of some small lakes by the scooping action of ice, 



VOL, XXVII. — PART I, . 2 I 



