642 MR. C. A. MATLEY ON THE [Aug. I 899, 



Mr. B. N. Peach has examined the fossils from the limestone- 

 blocks of the western Perth Padrig, and sends me notes concerning 

 them. The relationship of these blocks to the breccias in which 

 they lie will be dealt with later (p. 647), but it may be at once 

 mentioned that in Mr. Peach's opinion the limestone cannot be of 

 earlier date than Ordoviciau, and that it is in all probability of 

 Llandeilo age. He has no knowledge of the occurrence oi Stenopora 

 Jibrosa belo\\ the Llandeilo. Opercula of the Maclurea mafutina-type 

 are very common in the Durness Limestone, both in Sutherland 

 and Skye. M. magna, M. Logani, and M. macro mphala, M'Coy, are 

 found in the Stinchar Limestone, Ayrshire, which is either upper- 

 most Llandeilo or at the base of the Caradoc. At Mr. Peach's 

 suggestion, I sent some microscopic sections from this Perth Padrig 

 limestone to Dr. G. J. Hinde, who has very kindly examined them 

 and found that they contain Solenopora compacta, Prasopora Grayce 1 

 (both these forms occur in the Craighead Limestones of Girvan), 

 and a species of Monticulipora. 



(iii) Fossils south of the Green Series. 



In the central area south of the Green Series the fossiliferous 

 heds consist of basal conglomerates which rest unconformably on 

 older rocks or are faulted against them, and pass up through sand- 

 stones into black shales. The basal conglomerates and grits are 

 locally rich in the Orihis referred by Prof. Hughes and Dr. Davidson 

 to 0. Oarausii. Accompanying this species have been found frag- 

 ments of trilobites considered by Dr. Woodward and Dr. Callaway to 

 he lUcenus. Asaphus, and Ogggia, but by Prof. Hughes and Dr. Hicks 

 to be Mohe and Neseuretus} In several localities the black shales 

 have yielded graptolites.^ The lowest horizon indicated by them 

 in this central area is at Caemawr, where Didymogi^aptaa Miirchi- 

 soni occurs. From Llysdulas Climacograptus coelatus has been 

 identified; from Llanbabo Diplograptus (probably D. foliaceus), 

 Dicranograpjtus ramosus, Climacograptus Scharenbergi, DiceUog raptus 

 Morrisi, and Leptograptus sp. Prom the black slates of Parys 

 Mountain Monograpfus gregarius and other species belonging to 

 the M. gregarius-zone (Lower Birkhill) were obtained. At 

 Treiorwerth Henslow found some fossils, mostly brachiopoda, which 

 Prof. Hughes with some hesitation has also referred to a Llandovery 

 horizon. They appeared to the latter to include such forms as 

 Atrgpa mnrginalis, StropJiomena rJiomboidalts, Meristella angusti- 

 frons, Orthides including 0. calligramma (?) and var. plicata, Petraia 

 elongata f?J, and Nebulipora of. lens. 



In other parts of Anglesey, cut off from this central area by out- 

 crops of pre-Cambrian rocks, fossiliferous Ordovician strata occur.^ 

 Near Llangwyllog there are graptolites typical of the highest Arenig 

 or lowest Llandeilo. In North-eastern Anglesey Mr. Greenly has 

 found black-shale boulders with Climacograptus bicornis (?), and 



^ Quart. Journ. Geol. Soc. Yol. xl (1884) pp. 579 & 589. 

 2 Ibid. vol. sxxvi (1880) p. 238, vol. xxxviii (1882) p. 26, & vol. xl (1884) 

 p. 580. 



" Ibid. vol. xxxvi (1880) p. 238 & vol. Iii (1896) p. 628. 



