Baily — On Fossil Plants of Kiltorcmu 45 



them will be the same for each, of them, and the desired fixity of the 

 centre of the slit opening, and therefore of the spectral lines, with re- 

 spect to the pointer, is thereby secured. 



It is hoped that this instrument may be useful in the study of the 

 spectra of the Aurora and Zodiacal Light, which are not yet thoroughly 

 known ; the first on account of its caprscious variableness, the latter 

 by reason of its extreme faintness. The last-mentioned difficulty, 

 it is hoped, may be overcome, by the use of this special instrument, 

 which brings both the eyes into use, and by the improvement of an 

 opportunity which now offers for the study of the Zodiacal Light 

 under favourable circumstances, as regards climate, in the Mauritius. 



In conclusion, I have to thank Messrs. Stoney, Grubb, and Spencer 

 for numerous suggestions and improvements in the design of the in- 

 strument, and to apologise for the unavoidable haste with which this 

 notice has been drawn up, previously to my departure to Hodriguez as 

 one of the expedition to observe there the transit of Venus. 



YII. — On Fossils erom the Upper Old Red Sandstone of Kil- j/ 

 TORCAN Hill, in the County of Ejilkenny. Eeport ^o. 1. By 

 Wm. Helliek Baily, P. G. S., &c. 



[Read February 9, 1874.] 



Great interest in the fossil plants of Xiltorcan has been shown by 

 eminent scientific men, especially those of foreign countries, who have 

 made fossil botany their study ; and among those latter, with whom I 

 have corresponded on the subject, I may mention Professor Geinitz, of 

 Dresden ; Dr. Schimper, of Strasbourg ; Professor Heer, of Zurich ; 

 Principal Dawson, of Canada ; Professor De Koninck, of Liege ; and 

 M. Crepan, of Brussels— all of whom testify in their communications 

 to the scientific importance of investigating the subject. 



Additional interest arises not only from the perfect state of preser- 

 vation in which these fossils occur, but from the fact that they, with 

 their associated fossil fauna, assist in a material way to determine the 

 freshwater, or marine origin, of the great mass of old red sandstone 

 strata developed ia the British Islands, as well as on the continent of 

 Europe. 



Although this report relates more especially to the fossil j)lants, it 

 will not perhaps be thought irrelevant to allude to the associated animal 

 I'emains of mollusca, Crustacea, and fish discovered at the same place. 



The quarry from which the specimens now exhibited were collected, 

 in consequence of its remote situation, has not been much excavated,' 

 except for scientific purposes ; it is situated between Kilkenny and 

 Waterford, near the Ballyhale railway station, on an elevated ridge 



