Correspondence. 567 



carinifera, Siliquaria anguina, Cerithium vulgatum, Lima perversinn, 

 L. trilineatum, Buccwum macula, Pleurotoma rugulosum, Mitra ehurnea, 

 M. pUcatula, Dentalium strangulatiim. 



There is a sufficiency of Lusitaniau features in this assemblage 

 to make it referable to that older condition of the North Sea known 

 as the Crag Period ; instead of associating such a fauna with that of 

 Sternberg and Grafenberg, one object of my paper was to show that 

 there was no blending. 



The mystification as to Cassel arises from the same cause as it did 

 at the Bolderberg ; there is an admixture of fossils, but it is purely 

 accidental, owing to the lowest beds of one series (Kainozoic) having 

 been superimposed upon the uppermost beds of another (Tongrien). 

 This last has not been misunderstood by M. D'Orbigny (see Von 

 Koenen, p. 505), in whose geological scheme it is the latest and 

 uppermost marine assemblage of the great Nummulitic Period, and of 

 its Germanic sea area. 



M. D'Orbigny's only misconception consists in his placing his 

 " Tongrien " as a " sous-etage " of the •' Falunien." Into this he 

 was misled by the German authors. It is an error which may be 

 turned to good account by others, as showing how unsafe it is to 

 methodise from a bag of fossils gathered from the remanie beds of 

 one locality. Yours truly, 



EoBEKT Godwin-Austen. 

 Chilwokth Manor, Guildford, 

 November 19th, 1867. 



MR. WHITAKER ON " SUBAERIAL DENUDATION." 

 To the Editor of the Geological Magazine. 



Dear Sir. — I most unwillingly request of you to allow me space 

 to reply to some observations of my colleague, Mr. Whitaker, con- 

 tained in his paper " On Subaerial Denudation," published in the 

 number for October last ; and calculated to convey a very erroneous 

 impression of my views on this subject. Owing to a variety of cir- 

 cumstances, I had not read this paper, nor was I aware that any 

 personal allusion to myself was contained therein, until a friend 

 called my attention to the passage a few days since. In that passage 

 I find myself represented (p. 453) as "a strong believer in the sea, and 

 nothing hut the sea," as objecting to reasoning on logical principles, and 

 the writer concludes with the following : — " One should not be sur- 

 prised at the advocates of the marine formation of valleys and escar})- 

 ments looking down on logic, and scorning syllogisms, .... 

 unless they follow and overcome those prejudices which contracted 

 views of nature and magnified opinions of the experience of man 

 may have begotten," etc. What may be the meanmg of " following" 

 and " overcoming" a prejudice, is a question which may well be left 

 to those who alone are conversant with logical reasoning. 



If my critic had only taken the troulile to refer to my paper in 

 the Geological Magazine (Yol. Ill, p. 474) on " The Denudation 

 of the Yalleys of Lancashire," and to another paper to which refer- 



