332 DR WHEELTON HIND ON THE LAMELLIBRANCH AND 



While collecting the plants Mr Tait obtained a large number of specimens of 

 Lamellibranchiata, which were sent to me for identification. These were found in beds 

 exposed in the G-reenfoot Quarry, near Glenboig Station, Lanarkshire (Sheet 31, one- 

 inch map) ; in the river Avon, Linlithgowshire (Sheet 31) ; in Torwood Glen, Stirling- 

 shire (Sheet 31)*; and in Bilston Burn, Midlothian. At each of these localities 

 the lamellibranch fauna was found not far below the line which has been drawn 

 between the Upper and Lower Carboniferous floras, in accordance with Dr Kidston's 

 determinations. 



I was much surprised to meet with a lamellibranch fauna of which quite 50 per 

 cent, of the species were, as far as I could discover, new to Europe, but which resembled 

 very closely the lamellibranch fauna of the Coal Measures of Nebraska and Illinois of 

 North America. 



The most striking member of the fauna was the shell Prothyris elegans, Meek, this 

 being the first occurrence of the genus in the Carboniferous rocks of Great Britain. 

 Drevermann has described one species, P. bergica, from the lowest Carboniferous 

 rocks of Germany, Zeitsch. der Deutsche Geol. Gesel., vol. xiv., 1902, p. 498, pi. xiv. 

 In many cases it was impossible to distinguish any characters sufficient to separate the 

 Scotch and American species from each other, but it may be said that the faunas are 

 generically the same. Moreover, the lamellibranch fauna shows a marked approach to 

 Permian types. 



In North America the fauna is accompanied by Fusulina and Meekella, two fossil 

 genera which are absent in the West of Europe ; but both occur in the Spirifer 

 mosquensis zone of Russia, a zone which succeeds that of Productus giganteus in that 

 country. There does not, however, seem to be the least connection between the fauna 

 of the Spirifer mosquensis zone and that under examination. It is important to 

 ascertain the horizon at which this interesting fauna occurs in Scotland, that it may 

 be known where to look for its representatives elsewhere. At the outset there is a 

 great difficulty, and one that must be grappled with in the near future. 



The Lower Limestone series of Scotland contains the same coral fauna as the 

 uppermost division of the Carboniferous Limestone of England, or its equivalent farther 

 north, the Yoredale series, that is to say, the Dibunophyllum zone. The question at 

 once arises, What are the homotaxial equivalents of the Edge Coal series and the Upper 

 Limestone series of Scotland, south of the Border ? This question can only be satis- 

 factorily settled on palseontological lines. 



There is the most striking difference between the lamellibranch fauna of the Scotch 

 beds assigned to the Millstone Grit, and that which characterises the Millstone Grits 

 and the Pendleside series of England and Ireland. Here the upper beds of Carbon- 

 iferous Limestone, the Oyathaxonia beds, which themselves are the highest subdivisions 

 of the Dibunophyllum zone, are succeeded by black shales and limestones with 



* A preliminary statement referring to this collection of lamellibranchs was published in the Summary of Progress 

 of the Geological Survey for 1905, pp. 147 and 148. 



