376 Reports and Proceedings — 



(2) Bargany Group, of pale flagstones, shales, and mudstones, witli Eetiolites 

 Geinitzianus, Cyrtograptus Grayi, etc. 



(1) Fenkill Group, of purple mudstones, grey flags, and greywackes, with 

 Crossopodia, Protovirgularia, etc. 



(C.) Newlands Series (1000 to 1500 feet), embracing the 



(3) Camregan Group, etc., of yellow thick-bedded grits and dark shales, with 

 a band of calcareous rock ; abounding in Pentamerus oblongus, Afrypa 

 reticularis, Rastrites maxinms, and Monograptiis Sedgwickii. 



(2) Saugh-Hill Group, composed of alternations of coarse pebbly grit and 

 zones of grey and black shales, with a coarse conglomerate at the base. Its 

 commonest fossils are Stricklandiida lens, Pentmnerus oblong us, Favosites 

 gothlandicus, Monograptus leptotheca, etc. 



(1) Mulloch-Mill Group, formed of shelly sandstones underlain by a coarse 

 boulder-conglomerate, and containing hosts of Brachiopoda, etc., chiefly 

 Merlstella angustifrons, Atrypa hemisphcerica, Nidtilites favus, etc. 



Lower Girvan Rocks. 

 (B.) Ardmillan Series (1800 to 2000 feet), embracing the 



(4) Prummuck Group of soft grey mudstones, etc., with Trinucleus setieornis, 

 Ainpyx, Stnurocephalus, Bicellograplus, etc. 



(3) Barren or Shalloch Flagstones. — A great thickness of alternations of grey 

 or green flagstones and shales, generally destitute of fossils. 



(2) Whitehouse Group. — Purple and green shales and mudstones, striped flag- 

 stones and calcareous beds, with Pionide, Pindyniene, ^glitia, Agnostus, 

 Pictyonema, Picellograptus, and Fleurograptus. 



(1) The Ardwell Group of dark Graptolitic flagstones and shales, with oc- 

 casional fossiliferous seams affording examples of Picranograptus, Lepto- 

 graptus, and Climacograptus , etc. 



(A.) Barr Series (800 to 1000 feet), composed of the 



(4) Balclatchie Beds. — Highly fossiliferous pebbly grits and nodular shales, 

 with Pingula Ramsayi, P. canadensis, Siphonotreta micula, Pemopleurides, 

 Glossograptus, etc. 



(3) Benan {or Green) Conglomerate. — Massive boulder-beds of great thickness, 

 unfossUiferous. 



(2) Stinchar (or Craighead) Pimestone Group, composed of compact lime- 

 stones, nodular and calcareous flagstones and shales, with Maclurea Logani, 

 Ophileta, Orthis confinis, Tetradium, Pidymograptus, Clathrograptus, etc. 



(1) Kirkland [or Purple) Conglomerate. — Coarse boulder-beds and sandstones, 

 generally of a purple colour. 



Ifc was shown that the highest beds of this succession are faulted 

 against strata of Carboniferous age. The discussion of the relation- 

 ship of its lowest beds to the igneous and metamorphic rocks of 

 Ballantrae was deferred to a future paper. The author pointed out 

 how perfectly this reading of the succession explained the anomalies 

 hitherto supposed to obtain among the fossils of the Girvan region. 

 When the organic remains collected from these strata by previous 

 investigators (notably the magnificent Gray collection) are referred 

 to their natural horizons in this stratigraphical succession, it is 

 found that each of the great petrological divisions of the- Girvan 

 series has a collective fauna peculiarly its own, and that the general 

 zoological gradation is identical with that of the acknowledged 

 sequence in the typical Lower Paleeozoic ax-eas in Wales and the 

 West of England. 



The Lower Girvan rocks are clearly of Ordovician age ; while the 

 Upper Girvan rocks as distinctly appertain to the Silurian. The 

 Barr Series corresponds to part of the Llandeilo-Bala of Wales ; and 



