Preside7bfs Address. 93 



the Bivalves. Mr Young mentions JVaticojms as liaviiig 

 been so found, wliilst Dr J. S. Hunter possesses a specimen, in 

 his '* Braidwood Collection," of Tychonia (Naticopsis) Omal- 

 iana (De Koninck) from the Lingula beds of the Lower 

 Limestone Group, with colour bands preserved.* Professor 

 de Koninck has recently given a figure of his Naticopsis 

 projnnqioa,-^ exhibiting numerous spiral bands of colour. 



The best-marked example of this nature amongst Scotch 

 Carboniferous Univalves is perhaps a small shell found two 

 or three years since by Mr James Bennie, at Craigkelly 

 Quarry, near Burntisland, in the Calciferous Sandstone Series. 

 This has been named Platyostomella Scotohurdigalensis,\ and 

 possesses colour bands on the body whorl only, arranged botli 

 horizontally and vertically to the longer axis of the shell, but 

 not in the same individual. The horizontal bands are two 

 in every case, one at the periphery of the whorl, the other 

 lower down towards the base. In the variety with the bands 

 vertical, the latter are much more numerous, and they follow 

 and coincide with the lines of growth. § 



Finally the Cephalopoda occasionally show traces of colour 

 on their shells. Mr Young has met with an Orthoceras in 

 this condition. 



In previous pages we have made some remarks on the 

 Stunted Growth of many of the Scotch Carboniferous 

 Mollusca. 



That able Conchologist, the late Mr M'Andrew, has stated, 

 " Although the size obtained by Mollusca may be influenced 

 by various conditions in different localities, as a general rule 

 each species attains its greatest size as well as its greatest 

 number in the latitude best suited to its development." II 



The views of those who have studied the distribution of 

 the shells w^e are now considering, more particularly the 

 Brachiopoda, appear to coincide in attributing this decreased 



* "The Geology of the Carboniferous Strata of Carluke" (Trans. Geol. 

 Soc, Edinb., 1868, i., pt. 1, p. 51). 

 t Gast^ropodes, t. 1, f. 27, 28. 



X Etheridge, Proc. Koy. Phys. Soc, Edinb., 1880, p. 164. § Ihid. 



II See Davidson, Geologist, iii., 1860, p. 237. 



