140 PROF, J. W. JUDD ON THE OLIGOCENE 



in 1825*, and fully confirmed by Mr. S. P. Pratt in 1835 f, and by 

 Prof. Owen in 1841 :(:), established the fact of their general parallelism 

 with the upper portion of the series seen in the Paris basin. 



The first step towards the rectification of the classification of 

 the fluvio-marine strata was made by Mr. Prestwich in the year 

 1846. In a short but very suggestive and valuable paper §, he showed 

 that at Hamstead and Bouldnor Cliffs, in the Isle of Wight, there 

 occurs a series of estuarine and freshwater deposits, which he re- 

 garded as overlying the whole fiuvio -marine series, and which con- 

 tains, as he pointed out, a fauna of distinct character from that of 

 the underlying beds. 



Although many details concerning the several strata were ob- 

 served and described in succeeding years by Mr. Searles Y. Wood, 

 Dr. Wright, and the Marchioness of Hastings, both in the Isle of 

 Wight and on the opposite coast of Hampshire, while great additions 

 were made to our knowledge of the reptilian and mammalian fauna 

 by these and other authors, yet no new step in advance was made 

 in the classification of these beds till Edward Eorbes turned his 

 attention to the subject in the year 1852. In the meanwhile the 

 difficulty of harmonizing the accepted classification of the Hamp- 

 shire beds with the divisions established by accurate observers 

 in various parts of the Continent was strikingly illustrated by 

 the discordant results arrived at by such able students of Terti- 

 ary geology as Constant Prevost||, d'ArchiacIf, Dumont**, and 

 Hebertft. 



Porbes's careful study of the relations of the beds exposed in the 

 cliff-sections of the Isle of Wight, combined with his thorough and 

 critical examination of the fossils collected at diff'erent horizons, 

 enabled him to establish two very important points. In the first 

 place, he confirmed Mr. Prestwich's determination that the strata 

 exposed at Hamstead and Pouldnor Chfis overlie and are of younger 

 age than all the other strata of the fluvio-marine series. Por this 

 upper series of strata, which he showed to contain a very distinct 

 and characteristic assemblage of fossils, Porbes proposed the name 



* " On the Discovery of Anoplotherium commune in the Isle of Wight. By 

 the Eev. Prof. W. Buckland," Ann. of Phil. ser. 2, vol. x. p. 360. 



t " Remarks on the Existence of the Anopl other mm and PalcBotheriicm in the 

 Lower Freshwater Formation at Binstead, near Ryde, in the Isle of Wight. By 

 S. P. Pratt," Trans. Geol. Soc. ser. 2, toI. iii. p. 451. 



I "Description of some Fossil Remains of Chceropotamus, Talceotherium, 

 Anoplotherium, and Dichohune from the Eocene Formation, Isle of Wight. By 

 Prof. R. Owen," Trans. Geol. Soc. ser. 2, vol. vi. p. 41. 



§ " On the Occurrence of Cypris in a part of the Tertiary Freshwater 

 Strata of the Isle of Wight," Rep. Brit. Assoc, for 1846, Trans, of Sections, 

 p. 66. 



II "Coupe d'Alum Bay et d'Headen-Hill, dans I'ile de Wight," Bull. Soc. 

 Geol. France, t. viii. p. 76. 



^ " Note sur les Sables et G-res Moyens Tertiaires," Bull. Soc. Geol. France, 

 t. ix. p. 54. 



** " Essai sur la co-ordination des terrains tertiaires du Nord de la France, 

 de la Belgique, et de I'Angleterre," Bull. Soc. Geol. France, t. x. pp. 158, 168. 



tt " Comparaison des Couches tertiaires inf^rieures de la France et de I'An- 

 gleterre," Bull, Soe. Q-^ol. France, ser. 2, t. ix. p. 350. 



