Geological Society of London. 237 



Sir P. Egerton corroborated Mr. Etheridge's views as to the localization of species 

 of fish, and agreed with him as to the importance of recording* the exact position of 

 all such fossils. 



Prof. Eamsay was gratified to find that these connecting links between different 

 genera were being discovered. They seemed to him to foreshadow the time when 

 the word 'genus' would become extinct; while at the same time the careful researches 

 of the author and others tended more and more to establish the truth of the great 

 theory of evolution. 



2. '* On two specimens of Ischyodus, from fhe Lias of Lyme 

 Kegis." By Sir P. de M. Grey -Egerton, Bart., M.P., F.E.S., F.G.S. 



In this paper the author noticed a new example of the greatly 

 developed rostrum of a male Chimaeroid, an inch shorter, more 

 slender, and more attenuated at the apex, than that of Ischyodus 

 orihorhinus, Egerton, having a projecting median rib along the upper 

 surface, and the tubercles of the lower part smaller and fewer than 

 in J. orihorhinus. For this form the author proposed the name of 

 I. leptorhinus. Also a dorsal fin-spine, with the cartilages to which 

 it was articulated, showing the mechanism of its attachment very 

 clearly. This spine differs from that of I. orihorhinus in being 

 straighter and smoother, and having fewer and smaller tubercles. 

 The author regarded it as probably belonging to I. leptorhinus. 



3. ''How the Parallel Eoads of Glen Eoy were formed." By 

 Prof. James Nicol, F.G.S. 



In this paper the author endeavoured to explain, in accordance 

 with the marine theory of the origin of the parallel Eoads of Glen 

 Eoy, the coincidence of the level of these terraces with that of the 

 different cols, and also how the same sea could have produced ter- 

 races at different levels in different valleys. He assumed that 

 during the gradual elevation of the land, the gradual closing of the 

 straits between its separate masses by the elevation of the cols above 

 the surface would, by checking the eastward flow of the tidal current, 

 cause the sea-level in the western bays to remain stationary relatively 

 to the rising land ; and during this period the marine erosion would 

 take place along a line corresponding in level to the col. Hence, in 

 Glen Gloy, which has only one col, the highest in the system, the 

 highest road only was formed ; and Glen Gloy remained unaffected 

 by the stoppage of those cols which produced three roads at lower 

 levels in Glen Eoy, the lowest of them also extending round Glen 

 Spean, 



Discussion. — Sir Henry James stated that he had given particular instructions to 

 the officers in charge of the survey as to the accurate levelling of the roads. Captain 

 White had informed him that there was some question as to the existence of more 

 than one road in Glen Gloy. There could, however, be no doubt as to the general 

 correspondence of the levels of the terraces at different points. With regard to local 

 variations in the level of the sea, he stated that the mean sea-level was found to be 

 remarkably constant. He considered the question as rather physical than geological. 

 In that district was a country every feature of which had been modified by glaciers ; 

 and there was, therefore, no difficulty in conceding the existence of glacier lakes. 

 There was, moreover, every probability of a country cut up by such deep valleys 

 having in places enormous accumulations of ice. The difference in level between the 

 beds in Glen Gloy and Eoy was 20 feet, which could hardly be accounted for on the 

 marine theory. Nor are there any similar terraces in neighbouring glens, such as 

 ought to be there on that theory. In so exceptional a district, with Een Nevis acting 

 as a buttress at the south end of Glen More, against which and upon which ice 



