TBANSACTIONS OF SECTION C. 523 



Middle Headun of Whitecliff Bay. — It has been stated that the Colwell Bay bed 

 is placed iu tlie Brockenhurst, which is said to occupy a higher horizon than the 

 Headon Hill and Hordwell marine bed. The true place of the Brockenhurst fauna 

 in the Isle of \^'ight is confined to one zone, and that at the base of the Middle 

 Headon series, and only at Whitecliff Bay or in the New Forest. 



The Geological Survey do not mention by name the Brockenhurst bed in their 

 vertical section [Sheet 25] of Whitecliff Bay, as its peculiar fauna had not been 

 recognised at that time. It is easily identitied, however, in their section as the 

 basement bed of then- Middle Headon, the whole of which is given as 90 feet 

 thick. 



Brockenhurst Zone at Whitecliff Bay. — At the time the Geological Survey sec- 

 tion was made, this bed at Brockenhurst was unknown, and its fauna undescribed. 

 Subsequent observers have recognised the Brockenhurst fauna in the lowest bed 

 (2 feet thick) of the Middle Headon at AVhitecliff Bay. 69 species are known 

 here, and 104 occur at Brockenhurst. 



Affinities of the Brockenhurst Fauna. — If we take the whole Brockenhurst fauna, 

 including the eighteen corals (special to the zone) we obtain a total of 151 species, 

 of which from 74 to 81 pass up from Barton. 



Messrs. Tawney and Keeping supply a list of 53 species from the Brockenhurst 

 zone obtained from the Whitley Eidge Railway Cutting, New Forest. 51 of these 

 53 forms have occurred in the 2-foot bed at Whitecliff Bay, 27 of which pass up 

 from the Barton or Bracklesham beds. 



The palseontological evidence therefore accords with the stratigraphical. 



jRelation of Colwell Marine to Brockenhurst Fauna. — Examination gives us 

 29 per cent, of Barton forms in the Colwell Bay bed. In the Brockenhurst bed 

 the ratio was about 50 per cent., and in the Headon marine bed, 29 per cent. Ex- 

 amination also of the more characteristic Colwell and Headon marine fossils shows 

 that these faunas are practically identical — and also shows that only certain Brocken- 

 hurst species occur at Colwell Bay, and not at Headon Hill. They are Scalaria tessel- 

 lata and Tellina affinis, this latter a Barton form, while those occurring at Headon 

 Hni and not at Colwell Bay are Marginella (cstuarina and Cardita paucirostata ; only 

 ' two in each case, which amounts to perfect equality.' If we take into account those 

 common to the Colwell and Headon marine beds, and not occurrmg at Brockenhurst, 

 we iind twenty-six species. It is therefore evident that the Brockenhurst fauna is 

 not identical with that of the Colwell Bay bed, and not newer than that of Headon 

 Hill.^ 



Thus fossil as well as stratigraphical evidence shows that the Colwell Bay bed 

 is identical with the Headon Middle Marine. 



The same twofold proof demonstrates that the Brockenluirst bed, where present, 

 lies at the base of the Middle Marine Headon beds, and immediately above the 

 Lower Headon. This Brockenhurst bed is absent at Colwell Bay and Headon HiU, 

 but occurs at Whitecliff' Bay, Brockenhurst, and Lyndhurst. 



The proposal by Professor Judd to extend the name of the Headon series so 

 as to include all the beds between the Barton and Brockenhm-st series, and call 

 them the 'Headon Group,' woxdd cause great inconvenience. The term Middle 

 Headon, based as it is on the classical work of Edward Forbes, is clear and de- 

 finite. Again, it would entail the abandonment of the names Upper and Lower 

 Headon also; and the non-occurrence of the Brockenhurst series, or its repre- 

 sentative, in Colwell Bay admits of no recognition on the west side of the island, 

 and therefore the classitication would be based upon a defective appreciation of 

 the beds. 



Von Konen, in 1864, justly correlates the fauna, and since then, in 1866, the 

 coral fauna has been described by Dr. Duncan. 



Messrs. Tawney and Keeping, in their paper on the beds at Headon Hill 

 and Colwell Bay in the Isle of Wight, uphold the work done by the Geological 

 Survey, maintaining the correctness and integrity of the two Survey Memoirs, and 

 the horizontal and vertical sections of the Tertiary beds of the Isle of Wight. Pro- 

 fessor Judd differs from the identifications and stated succession of the beds in 

 Totland and Colwell Bays. He introduces two new series at Headon Hdl, a marine 



