380 Reports it Proceedings — Mineralocjical Society. 



The Abbey Shales appear to have been deposited in ratbera sliallow 

 sea, in which slight changes in conditions introduced marked 

 variations in the rock-types. Corresponding to these alternating 

 physical conditions there occur alternations of faunas — a good 

 example being afforded by Aptostus rex, found in the coarse shales, 

 and A. {Ct.) intermedius, found in the blue shale. 



Towards the close of the Middle Cambrian Period excessive 

 shallowing of the water introduced a period of marine erosion — 

 causing a break in the sedimentary sequence with the elimination of 

 the equivalents of the P. forchhammeri zone, and in some cases 

 a portion of the P. davidis zone. This break appears to have 

 extended over a large part of Great Britain. Attention is drawn to 

 the fact that none of the characteristic forms which occur exclusively 

 in the rich P. forchhammeri zone of Scandinavia have been noted from 

 any locality in Great Britain. 



2. " The T'rilobite Fauna of the Middle Cambrian of the 

 St. Tudwal's Peninsula (Carnarvonshire)." By Tressiliaii Charles 

 Nicholas, B.A., F.G.S. 



In a previous paper on the geology of the St. Tudwal's Peninsula 

 approximate determinations were given of the fossils found in the 

 Upper Caered Mudstones and Nant-pig ]\Iudstones, both of Middle 

 Cambrian age. The object of the present paper is to give detailed 

 descriptions of several forms which are either new or of particular 

 interest : namely, Affnostus hjerulfi, two new species of Agnostus, 

 a species of Agraulos, of Dorypyge, of Corynexochus, and Solenopleura 

 applanata, and to give brief notes on a number of other species, 

 including Agnostus punctuosus, A. exaratus, A. fissus, A. alius, 

 A. truncatus, Microdiscus pmictatus, Conocoryphe cf. dalmani, and 

 Paradoxides hicks ii. 



The vertical distribution of the different forms through the Upper 

 Caered and Nant-pig Mudstones is tabulated and compared with that 

 of other areas, particularly the succession recently established by 

 Mr. V. C. Illing in the Abbey Shales of Nuneaton, This comparison 

 strengthens the opinion already put forward in the previous com- 

 munication, that there is a non-sequence at the base of the Lingula 

 Flags in the St. Tudwal's Peninsula. 



III. — MiNEKALOGICAL SoCIETY. 



June 16, 1914.— Dr. A. E. H. Tutton, F.E.S., President, in the Chair. 



Dr. J. Drugman : . Childrenite from Crinnis Mine, Cornwall, and 

 Eosphorite from Poland, Maine. Analysis of childrenite from Crinnis 

 Mine showed it to contain even less manganese than the specimens 

 from George and Charlotte Mine. Eosphorite from Poland is richer 

 in manganese than that from Branchville, the only occurrence 

 previously known. It is well crystallized, unlike the Crinnis Mine 

 childrenite. — E. H. Solly : On Sartorite. From a geometrical 

 examination of 200 crystals it is concluded that Dr. Trechmann's 

 crystals, Nos. 1 and 2, belong to a new species closely allied to 

 sartorite and smithite. Many new forms for sartorite were found. — 



