162 A. R: Andrew—The Doilgelley Gold-belt. 
From the Pen Rhos Beds ; the Upper Maentwrog of Beit. 
B  Agnostus pisiformis (Linn.). BO. truncatus (Angelin). 
B  Olenus cataractus (Salt.). SO. sp. 
S 0. micrurus (Salt.). S  Lingulella Davisii (McCoy). 
From the Vigra Beds; the Lower Maentwrog of Belt ; the Cwm Hisen of Plant. . 
Agnostus nodosus (Belt). S Hymenocaris vermicauda (Salt.). 
Ss 
BA. pisiformis (Linn.). P,S Olenus cataractus (Salt.). 
P,S A. princeps (Salt.). S 0. gibbosus (Wahl.). 
PA. trisectus (Salt.). P Sao hirsuta. 
1Y S Lingulella Davisii (McCoy). 
From the Clogau Beds; the Menevian of Salter and Belt ; the Tyddyn-Gwladys of 
Holocephalina sp. 
Plant. 
P Protospongia fenestrata (Salt.), P Leperditia sp. 
P Dictyonema sp. (?). P,S Microdiscus punctatus (Salt.). 
P Agnostus Davidis (Salt.). P Paradoxides Davidis (Salt.). 
PA. pisiformis (Linn.). PP. Forchhammeri (Angelin). 
P A. princeps (Salt.). P,S P. Hicksii (Salt.). 
P A. trisectus (Salt.). P Lingulella ferruginea (Salt.). 
IP Area. P Obolella sp. 
P Anopolenus Henrici (Salt.). P  Obolus sp. 
P A. Salteri (Hicks). PP Theca corrugata (Salt.). 
S Conocoryphe sp. 
Petrology and Mineralogy.—References to the petrology of the 
igneous rocks of the district will be found in the writings of Salter 
(20, p. 2), Forbes (25, 26, 27), and Teall (28). 
A large number of minerals have been reported at various times 
from Merionethshire, chiefly by Readwin (80, 31), Forbes (25, 
p- 226; 27), and by Huddart (85). A list of these minerals is given 
below: unless otherwise indicated, the report of the occurrence of the 
mineral is to be found in one of Readwin’s notices. 
Native Elements: Gold, Electrum, Silver, Platinum, Platiniridium, Iridosmine, 
Copper, Lead (Forbes), Antimony, Bismuth. 
Sulphides, Tellurides, etc. : Orpiment, Stibnite, Bismuthinite, Tetradymite, Galena, 
Sphalerite, Erubescite, Pyrrhotite (Huddart), Pyrites, Chalcopyrite, Marcasite, 
Arsenopyrite, Berthierite, Tetrahedrite, Aphthonite, Polytelite (Fordes). 
Oxides: Quartz, Arsenolite, Senarmontite, Magnetite, Titanoferrite, Rutile. 
Carbonates: Calcite, Dolomite (Forbes), Ankerite (Forbes), Chalybite (Forbes), 
Rhodochrosite, Cerussite, Malachite. 
Silicates: Orthoclase, Hornblende, Uralite, Mica, Chlorite (Forbes), Ripidolite, Talc. 
Phosphates: Pyromorphite, Mimetite. 
Sulphates: Barytes (Forbes). 
Mining.—In 1844 Dean (36) and Roberts (37) published the first 
notices relating to the discovery of gold in Merionethshire. During 
the years 1870 to 1880 Readwin published many articles in the 
Mining Journal and elsewhere, giving many details of the mining 
industry (32, 33). In 1902 Maclaren (38) brought together many 
interesting facts regarding the Merioneth field. Other references 
to the mining industry of Merionethshire are to be found in the 
writings of Forbes (25), Booth (89), Huddart (35). 
STRATIGRAPHY. 
The divisions and groups which have been adopted in the present 
paper are those of Lapworth and Wilson for the Lower Cambrian and 
