150 PROF. J. W. JUDD ON THE OLIGOCENE 



indorses the opinion of Hebert and Mayer as to the distinctness and 

 importance of this division of the Lower Tertiary series.* 



When we come to study the whole of the marine forms of Headon 

 Hill and Hordwell, and to compare them with those of the Brocken- 

 hurst, Colwell-Bay, and Whitecliff-Bay beds, the distinction of the 

 two faunas becomes strikingly apparent. Nearly one hundred 

 marine forms are known from Headon Hill and Hordwell, while 

 almost twice that number have been obtained from the New-Forest 

 localities, Colwell Bay, and Whitecliff Bay. Of the forms found 

 at Headon Hill and Hordwell Cliff, less than one half occur at the 

 three other places. Again, if we compare both of the marine faunas 

 with that of the Barton series, we find that while nearly one third 

 of the Hordwell and Headon-Hill marine shells are Barton forms, 

 not more than one fifth of those occurring at Brockenhurst, Colwell 

 Bay, and Whitecliff Bay are found at Barton. On the other hand 

 the latter fauna has more species in common with that of the 

 Hempstead beds than has the former. 



Summing up the results of this palseontological examination of the 

 beds, we find that the fossils in the Headon-Hill and Hordwell-Cliff 

 beds are almost identical, while those of Colwell Bay, Whitecliff Bay, 

 and of the New Forest localities also present the very closest agree- 

 ment with one another. But when we come to compare the fauna 

 of the two first-mentioned places with that of the other three, we 

 are struck by remarkable points of difference. In the first place, the 

 conditions indicated by the former are estuarine, of the latter purely 

 marine; secondly, more than one half of the forms found in the 

 former are different from those in the latter ; thirdly, the former 

 exhibits a much closer approximation to the Barton fauna than does 

 the latter ; and, fourthly (and most important of all), the fauna of 

 the former agrees with that of a series of beds occurring both in 

 France and Germany, which unquestionably underlie and are of 

 older date than beds containing the fauna of the latter. We thus 

 see that the palaeontological evidence fully supports the conclusion 

 derived from a study of the physical evidence — namely, that the 

 Hordwell-Cliff and Headon-Hill strata are not, as has previously been 

 supposed, on the same horizon with those of Brockenhurst, Colwell 

 Bay, and WhiteclifE Bay, but occupy a distinct and lower place in 

 the geological series. 



V. COEEELATION OP THE StRATA WITH FoREIGN BeFOSITS. 



Since the date of the appearance of Edward Forbes's posthumous 

 monograph ' On the Tertiary Fluvio-marine Formation of the Isle 

 of Wight,' so much has been done in the investigation of the faunas 

 and floras t of the several divisions of the series, and at the same 



* Sandberger, ' Land- u. Siisswasser-Conchylien dei- Yorwelt,' p. 198. 



t The valuable collection of Lower Tertiary fossils made with such un- 

 tiring industry by the late Mr. F. E. Edwards, and in part described by him- 

 self, Mr. S. V. Wood, and Dr. Duncan in the publications of the Paleeontogra- 

 phical Society, have fortunately been acquired for the nation, and are now in 



