142 TROP. J. W. JTTDD ON THE OLIGOCENE 



SO many of the fossils of the Lower Tertiary formations. Owing to 

 their labours and those of other indefatigable collectors, the num- 

 ber of known fossil forms from the fluvio-marine beds is at least 

 four times as great as was recognized by Edward Forbes. 



At the same time the remarkable fauna of Brockenhurst, in the 

 Kew Porest, which was discovered by Mr. Edwards, has been care- 

 fully studied by Yon Konen* and Dr. Duncan f, who have shown 

 the exact agreement of this fauna with that of the Lower Oligocene 

 in Northern Germany ; while the Eev. Osmond Eisher J and Mr. H. 

 M. Jenkins § have recognized its identity with that of certain strata 

 in the Isle of Wight. 



Last, but not least, must be mentioned the great advances which 

 have been made in our knowledge of the faunas of equivalent strata 

 upon the continent of Europe, especially those which we owe to the 

 researches of Deshayes in the Paris basin, of Sandberger in the 

 Mayence basin, and of Homes in the Vienna basin, which have 

 supplied valuable means of comparison between the English and 

 foreign strata, such as were almost wholly wanting when Eorbes was 

 engaged in the study of the Isle-of- Wight beds. Eurtheimore, many 

 able geologists, among whom may especially be mentioned M. Hebert 

 in France, MM. Charles Mayer and Renevier in Switzerland, MM. 

 Sandberger and Beyrich in North Germany, and M. T. Fuchs in 

 Austria, have occupied themselves with the question of the corre- 

 lation of the various European Tertiary deposits with great success. 



Under these circumstances we are now supplied with the means 

 for making a much more exact and rigid comparison of the strata 

 of the Hampshire basin vrith those of the other European areas 

 than was possible twenty-five years ago. Foreign geologists, who 

 have endeavoured to correlate the British deposits of this age with 

 their equivalents on the continent, have experienced the greatest 

 difficulties, owing, as I believe, to the succession of beds in this 

 country having been hitherto misunderstood. It is on these grounds 

 that I venture to offer a new classification of these strata as the 

 result of researches which I have carried on for some time past. 



III. Steatigeaphical Evidence. 



We have stated that hitherto a serious error has been made in 

 reading the succession of strata exposed in the cliff-sections at the 

 western extremity of the Isle of Wight. The beds seen at ColweU 

 and Totland Bays have been regarded by nearly all observers as 

 being upon the same geological horizon as those exposed at the base 

 of Headon HiU, whereas, as I shall now proceed to show, the latter 

 altogether underlie the former. The primary cause of this mistake 

 concerning the succession of these beds is not difficult to discover. 



* " On tlie Correlation of the Oligocene Deposits of Belgium, Northern Ger- 

 many, and the South of England," Quart. Journ. Geol. Soc. vol. xx. p. 97. 



t ' A Monograph of British Fossil Corals,' 2nd series, Palaeontographical 

 Society, 1866. 



I Quart. Journ. Geol. Soc. vol. xviii. p. 67, footnote. 



§ Quart. Journ, Geol. Soc. vol. xxiv. p. 519. 



