Notices of Memoirs — W. WMtaker's Address. 23 



These doubts I expressed in my Monograph,^ and acting on the 

 evidence of the age (Devonian), and the published figure of Schlot- 

 heim's specimen, I restored Phillips' specific name of gemmulifera 

 for this Carboniferous Limestone form, and discarded that of Schlot- 

 heim (T. pustulatus) as untenable. Having latel}^ seen and con- 

 sulted my friend Prof. Dr. Ferdinand Roemer, of the Mineralogisches 

 Museum, Breslau, our highest authority on the fossils of the Eifel, 

 he very kindly promised me, on his return journey, in passing 

 through Berlin to Breslau, to compare my figures of FMllipsia 

 gemmulifera with Schlotheim's specimen of Trilob. pustulatus in the 

 Berlin Museum. I now have the pleasure to append his letter, 

 which entirely sets the matter at rest. 



" Mineralogical Museum of the Royal University of Breslau. 

 Dear Dr. Woodward, — Schlotheim's Trilobites pustulatus is nothing 

 else than a pygidium of Phacops latifrons from the Eifel. This is 

 proved beyond any doubt by Schlotheim's original specimen in the 

 Berlin Museum. — Yours very truly, 



"{17th October, 1883.) Ferd. Eoemee." 



isroTiGiBS oip nvc:E:vi:oiE,s. 



Some Geological Conditions Affecting the Question of 



Water Supply from the Chalk. 



[Part of the Presidential Address to the Norwich Geological Society, 6 Nov. 1883.] 



By W. Whitaker, B.A., F.G.S., of the Geological Siirvey. 



IT has occurred to me that I might profitably take as the chief 

 subject of m}'^ address one of practical importance, and one 

 showing that the detailed mapping of our county by the Geological 

 Survey, which is now all but finished, is not a matter of mere 

 theoretical interest. 



As our Survey will be finished this year, except for some questions 

 of revision in the western part of the county, and as some time next 

 year the officers of that Survey will be denuded from Norfolk, the 

 present seems a fit time for bringing forward such a subject. Were 

 the question put off for the publication of the whole of the Survey 

 Maps, it would be at least two years before it could be brought before 

 you, and though I suffer therefore from the want of great part of the 

 material needful for a full consideration of the question as regards 

 Norfolk, yet I think that we have enough to warrant its discussion, 

 especially as it can be illustrated by reference to other districts of 

 a like character. Indeed the amount of material in my hands is so 

 large that I have been unable to work it all up in time, and there- 

 fore have had to neglect some parts of the bordering counties of 

 Cambridge and Suftblk which I had hoped to have illustrated amongst 

 the maps before you. 



During the course of my work on the Geological Survey I have 

 paid some attention to the question of water-supply, and a few years 

 ago I had to make a set of maps for the purpose of showing the 



^ See Mon. Garb. Limestone Trilobites, 1883, part i. pp. 17-19, plate iii. figs. 1-8. 

 See also Geol. Mag. 1883, Decade II. Vol. X. Fig. 3, p. 450. 



