362 TERTIARY GEOLOGY OF NORFOLK, &C. 



have acted with so little prudence as not to have reserved a supply to 

 meet the demand that must arise when the work is rendered complete ; 

 and never intends, after the issue of his 15th livraison, to resume those 

 labours in ancient Ichthyology which have shed so much light upon this 

 department of science, and reflected so much lustre on himself ; in that 

 case most cordially should we adopt his avowed sentiments, and look up- 

 on a cheap English fac-simile of the ' Poissons Fossiles,' as a matter of 

 the highest 'utilite.' 



A paper from the pen of Mr. Lyell appears in our number for the pre- 

 sent month, which embodies some results of the highest interest, as bear- 

 ing upon the tertiary Geology of Norfolk and the adjoining counties. — 

 The district treated of has long been celebrated for the number and beau- 

 ty of its fossils ; but until within a very recent period, no suspicion had 

 been entertained that the fossiliferous beds called "crag" included depo- 

 sits of distinct geological ages. It is now, however, satisfactorily shown 

 by the application of the per-centage test to the very extensive series of 

 crag Testacea in the cabinet of Mr. Searles Wood, that three marine de- 

 posits, of different and well-marked periods, overlie the chalk and Lon- 

 don clay in this part of England. This result confirms the general views 

 upon Tertiary Geology which Mr. Lyell has entertained in opposition to 

 M. Deshayes, who asserts the existence in the tertiary group, of three de- 

 finite proportions in the percentage of extinct species, and to one of which 

 any member of the series may be referred. 1 



The misapprehension which has so long prevailed respecting the his- 

 tory of a formation that has so often been looked at with geological 

 eyes, proves the absolute necessity for extreme caution in deciding upon 

 the age of deposits that may be situated in less frequently explored loca- 

 lities. 



From the recently published annual reports of the Geological and 

 Zoological Societies, both these important scientific associations may be 

 considered in a flourishing condition. The former has been steadily in- 

 creasing in the amount of its members ; and though the latter has pro- 

 bably attained its maximum number, and suffered a serious diminution 

 of income from the unfavourable summers of the two past years, the re- 

 ceipts have still left a surplus over the expenditure. The Council of the 



J "4. Constant proportions (3 per cent., 19 per cent, 52 per cent.) in 

 the number of recent species, determine the age of the tertiary strata." 

 Deshayes; translated in Mag. Nat. Hist. vol. i. n. s. p. 12. 



