President's Address. 87 



of the Carboniferous System, some distance above tlie Curly 

 Ironstone. It is a seam of clay ironstone known as the 

 " Ginstone" or " Thomson's Balls/' with a well-marked marine 

 fauna, consisting of Froductns 7nartini, Discina niiida, 

 Lirigida mytiloides, Lcda aitcnuata, Niicula gihbosa, a Fleitro- 

 tomaria, a Goniatitc, and Conularia* 



According to Messrs Armstrong and Young, the only 

 instance of marine shells in a sandstone, known to them in 

 the West of Scotland, occurs near Glasgow. The sandstone 

 is white, and contains " the remains of several species of 

 Brachiopods, and various other shells, chiefly casts.""t- 



It will be observed from the above facts that the molluscan 

 fauna of the Millstone Grit is, in point of species, the most 

 limited we have met with, and almost wholly consists of 

 Brachiopoda. It is probable that the beds in which these 

 fossils are found represent marine inroads in an otherwise 

 almost entirely fresh-water deposit. 



The Coal Measures proper consist of the great mineral 

 bearing series of beds, and an upper section, termed the Eed 

 Sandstone Group, which is believed to be quite unfossili- 

 ferous.j 



The organic contents of the true Coal Measures consist of 

 fish, reptile and plant remains, with a few crustaceans, 

 insects, and a small development of molluscan life. The 

 latter, with the exception of organisms occupying a few 

 marine bands scattered throughout the series, consist wholly 

 of the characteristic Bivalves, AntJiracosia, AodJiirico2)fera, 

 and Anthracomya. Until comparatively recent years marine 

 .shells were unknown in the Coal Measures, for we find a ^Ir 

 R. Craig, writing in the year 1839,§ stating that the Upper 

 Coal Series does not " contain the slightest trace of marine 

 organic remains, the shells found in it being all referable to 

 the fresh- water genera Modiola, Anodonta, and Unio." Later 

 researches, however, have proved this notion to be fallacious, 



* Trans. Glasgow Geol. Soc, 18G8, iii., pt. 1, p. 108. 

 t Cat. W. Scot. Foss., p. 48. 

 It Mem. Geol. Survey, Scotl., No. 23, p. 93. 



§ "On the Carboniferous Formation of the Lower Ward of Lanarkshire" 

 (Trans. Highland Soc, 18159, vi., p. 345). 



