Revieus — Geological Survey Memoirs. 271 



II. — Three Geological Suktey Memoirs. 



The Geology of the Country around Mevagissey. By Clement 

 Eeid, F.R.S. ; with Petrological Contributions by J. J. H. Teall, 

 D.Sc, F.R.S. pp. yi, 73, with 7 plates and 4 text-illustrations. 

 Price 2s. — Colour-printed map, Sheet 353. Is. 6^?. 



The Geology of the Country around Plymouth and Liskeard. By 

 W. A. E. UssHER, P.G.S. ; with Notes on the Petrology of the 

 Igneous Eocks, by J. S. Plett, M.A., D.Sc. pp. vi, 156, with 

 4 plates and 15 text-illustrations. Price 3s. — Colour-printed map, 

 Sheet 348. Is. Qd. 



The Geology of the Quantock Hills and of Taunton and Bridg- 

 water. By W. A. E. TJssHEK, E.G.S. pp. iv, 109, with 15 text- 

 illustrations. Price 2s. — Colour-printed map, Sheet 295. Is. Qd. 



IN the first of these memoirs we have a description of the small but 

 complicated area extending from Tregoney to Veryan Bay and 

 Mevagissey Bay. It is a region made classic by the early discoveries 

 of * Silurian ' fossils by C. W. Peach, and has been more recently 

 referred to in the pages of this Magazine (July and August, 1904, 

 pp. 289, 403, and January, 1906, p. 33) by Mr. TJpfield Green with 

 the collaboration of Mr. C. D. Sherborn. 



Although fossils had been found by Peach at Porthluney, we owe 

 to Mr. Green the discovery of true Upper Silurian fossils in lenticles 

 of limestone at that locality, probably of both Wenlock and Ludlow 

 age. Interest naturally centres in the palaeontological evidence, and 

 we are glad to note the further important material gathered by 

 Mrs. Clement Reid from the Ordovician quartzite of Perhaver Beach. 

 By dint of much labour she obtained six species of trilobites, named 

 by Mr. Philip Lake— 



Cheirurus Sedgiuicki, Salt. Fhacops mimus, Salt. 



Calymene Tristani, Brongn. Phacops incertus (?), Desl. 



Calymene Camhrensis, Salt. Asaphtts Poivlsi (?), Murch. 



These species apparently represent beds of Llandeilo age, as noted by 

 Salter, who first identified the Calymene Tristani from the Cornish 

 strata. 



The geological map of Mevagissey gives but little idea of the 

 difficulties encountered in determining the structure in the cleaved, 

 crushed, overthrust, and broken sedimentary and igneous rocks ; and 

 as Mr. Beid remarks, "there is enough unexplained in this small 

 area to employ a skilled geologist for several years longer, and there 

 is also plenty of work for the fossil collector and petrologist." 



The author in describing the " Lower Palaeozoic Eocks " takes us 

 along the coast from the Dodman northwards to Gorran Haven and 

 Mevagissey, and westwards to Carne and Yeryan. The age of the 

 Dodman Series is not known, but there is evidence of a sequence from 

 the unfossiliferous Portscatho Series (of J. B. Hill) to the Veryan slates, 

 limestone, and radiolarian chert, and the Gorran or Carne quartzite, 

 which are of Ordovician age. Besting unconformably on the older 

 strata are coarse conglomerates, grits, and slates grouped as of Lower 

 Devonian age. Pictures of rock- structure are given, including pillow- 

 lava and slickensided quartzite ; also of honeycomb weathering, 



