THE CARBONIFEROUS BRACHIOPODA OF THE CLYDE 



DRAINAGE AREA. 



BY JAMES NEILSON. 



THE important group of Brachiopods is well represented in the marine beds 

 of the Upper and Lower Limestone series of the Clyde drainage area, 

 especially in the Lower Limestones, and the most finely preserved examples 

 are found in the associated shale-beds, showing in many cases the interior 

 structure and muscular impressions. The minute organisms have been 

 obtained in great abundance from the rotted limestone of the upper part 

 of the Lower Limestones near Beith in Ayrshire. 



The Middle Coal and Ironstone series, which lies between the above- 

 mentioned marine beds, and is chiefly of freshwater origin, is not known to 

 contain any brachiopods except a few specimens of Lingula mytiloides and 

 L. squamiformis, which occur in the alternating brackish-water beds. 



The Calciferous Sandstone series of the Clyde drainage area does not yield 

 any brachiopods, several species previously recorded from Arran being now 

 found to belong to the Upper and Lower Limestones. 



The boundaries of the Millstone Grit series are not as yet well-defined, 

 and the fossils recorded from it appear so low down in the beds, abutting on 

 the Upper Limestones, that it has been thought best to include them in the 

 list from that series. 



The remains of brachiopods, chiefly as casts, are found in a bed of hard, 

 white sandstone, exposed in a cutting on the North British Railway just 

 south of Garngad Station, Glasgow, and this is, so far as we know, the 

 only instance of the remains of marine mollusca having been met with in 

 sandstone belonging to the Western Scottish coal-field. 



One or two forms of brachiopods, e.g. Lingula, range upwards into the 

 lower strata of the Upper Carboniferous series, but are confined to thin bands 

 which do not contain any of its more characteristic forms. 



In 1865 a thin bed containing two species of brachiopods and some other 

 marine forms was discovered in the sinking of a coal-pit at Drumpark, about 

 200 fathoms above the Millstone Grit, but no similar occurrence has since 

 been noted. 1 



The arrangement adopted in the following list is that of the late Dr. 

 Thomas Davidson in his Monograph of " The British Carboniferous Brachio- 

 poda " issued by the Palaeontographical Society. The divisions of the rocks 

 in which the fossils occur are given before the localities in heavy letters. 



1 Trans. Geol. Soc. of Glasgow, vol. ii., 1865, p. 52. 



