92 Proceedings of the Royal Physical Society. 



radiating and fluctuating dark bands. These undoubtedly 

 represented colour bands on tlie shell when alive.* 



Another unarticulated Brachiopod exhibiting such traces 

 is Piscina nitida (Phill.). In this instance Mr Young found 

 them to consist of alternate radiating bands of blue and 

 white. The specimens were found at Boghead, near Ham- 

 ilton.! 



Amongst Bivalve Mollusca the genus Aviciolopecten ex- 

 hibits this character with the greatest frequency, although 

 colour markings have also been seen on Myalina.X The 

 i:)igment ornamentation of Scotch Aviculopectens has not been 

 described, although such have been found,§ but specimens 

 from the English mountain limestone have been so. A. 

 2')lanoradiatus possessed thin concentric bands passing into 

 blotches, and sometimes assuming a widely zigzag pattern. 

 In A. ? suhlohatiis the colour markings are better preserved than 

 in any other shell yet found. They are in the form of radiating 

 brown bands. They may be as few as six or seven, or as many 

 as fourteen or fifteen on one example, passing straight from 

 the beak to the margin, or becoming slightly flexuous in their 

 course. They are also of variable thickness, those near the 

 centre of the shell being the thickest, gradually decreasing 

 to the sides, and separated by intervals of varying breadth on 

 the same shell. They exist as plain bands, or each one bi- 

 furcates, or each alternate one does so, or, as in one solitary 

 example, the three central out of the seven bands are split 

 up into three thinner sub-divisions, uniting towards the beak. 

 Occasionally smaller bands are interpolated between the 

 larger, extending and becoming thinner upwards towards the 

 beak, from the margin, but not reaching the former. 1 1 



The remains of colour in the Gasteropoda, or Univalve 

 shells, are of much less common occurrence than even amonost 



* Proc. Nat. Hist. Soc, GLasgow, 1881, iv., pt. 2, p. 263. 



+ Davidson, Suppl. Mon,, p. 268. 



X Young, " On the Occurrence of Shells showing Colour Markings, from 

 the Carboniferous Limestone Strata of the West of Scotland " (Proc. Nat. 

 Hist. Soc, Glasgow, 1867, i., p. 185). 



§ Young, loc. cit. 



II Geol. Mag., 1876, iii., p. 151. 



