TRANSACTIONS OF SECTION C. 523 



Brockenliurst. Many species are confined to this horizon and do not pass up into 

 the ' Venus bed.' Thus the Brockenhurst fauna at Whitechff Bay numbers 70 

 species, at Brockenhurst 104, and of these only eig-hteen occur in the Middle 

 Marine beds of Colwell Bay, or are common to Whitecliff Bay and the type locality. 

 Eighty-three Barton or Bracklesham species pass up, twenty-five to the Middle 

 Marine of Colwell Bay, and thirty-si.t to the Brockenhurst bed of Whitecliff" Bay, 

 or these two localities yield the above number of Bartonian forms. To still 

 further illustrate the value of the Middle Ileadon series of the Isle of Wight and 

 elsewhere, I may mention certain characteristic fossils that occur in several 

 zones. The ' Venus bed ' of the Geological Survey is about thirty feet thick at 

 Colwell Bay, Headon Hill, and Whitecliff" Bay, and contains the "following well- 

 marked shells, Murex se.vdentatus, Melanin fasciata, Cerithiuni duplex, C. ventri- 

 cosum, C. concavum, and Nerita apertn. Shells characteristic of the Brockenliurst 

 bed and confined to it are Voluta suturalis, Leiostoma ovatum, Tecten hellicostatus, 

 Modiola nysti, Cyprina nysti, and Cytherea solandri, var. attenuata. In the Roy- 

 don zone occurs Voluta geminata, and nowhere else in England. Pleurotoma 

 tramversai-ia, P. suldenticulata , Cardita deltoidea, and Protocardium hantontense are 

 in both the Roydon and Brockenhurst zones, but not known in the Venus bed. 

 Certain species range through the Middle Headon series and occur nowhere else. 

 These are Pisania labiata, Pleurotoma headonensis, Cancellaria muricata, C. elongata, 

 Leda propinqua, Cytherea suborbicularis, Psammobia (estuarina, and Corbicula obo- 

 vata. The Brockenhurst zone is restricted to the lower 2 feet of the Middle 

 Headon, and it lies immediately on the eroded surface of the Lower Headon. An 

 error certainly has been committed in the New Forest section, in assigning the 

 place of the Brockenhurst series above the Middle Marine or Middle Headon. This 

 IS at variance with facts at Brockenhurst and Whitecliff" Bay, and this misappre- 

 hension as to the stratigraphical position of the Brockenhurst bed refutes the theory 

 as to the occurrence of this bed high up in Headon Hill. It is not in existence 

 there. 



With reference to the affinities of the Brockenhurst fauna, it has been stated 

 that ' nearly one-third of the Hordwell and Headon Hill marine shells are Barton 

 forms, and not more than one-fifth of those occumng at Brockenhurst, Colwell Bay, 

 and Whitecliff" Bay, are found at Barton.' We should not expect the Venus bed 

 or Middle Marine would have more Barton species than the Brockenhurst bed, seeing 

 that the former occupies a higher zone in the Middle Headon series. The percentage 

 of Barton forms, according to Mr. Tawney, in the Whitley Ridge bed, is 42 per cent. ; 

 a lower proportion than at Whitecliff" Bay, arising from the number of corals being 

 special to the Whitley locality. At Whitecliff' Bay the Barton group has 52 per cent., 

 and the proportion of Barton forms from all the Brockenhurst localities, including 

 the Roydon zone, is 48 per cent., and the percentage of the Barton forms in the Middle 

 Headon of Headon Hill is found to be 29 per cent. ; the conclusion therefore from 

 fossil evidence is that the Headon Hill marine lied is later in age, and higher 

 6tratigraphically than the Brockenhurst bed, the proportion of Barton forms in the 

 latter being nearly 50 per cent., and not one-fifth, as stated. The result is in strict 

 accordance with their stratigraphical positions. It is equally important to test by 

 fossil evidence whether the Colwell Bay Venus bed (Middle Headon) is more 

 nearly related to the Brockenhurst than is the Headon Hill bed. In Colwell Bay 

 the observed Barton forms are 29 per cent, in common, and the same percentage 

 in the Headon Hill bed, while in the Brockenhurst bed they were 48 per cent. To 

 test still more the proof from palaeontological evidence, it is stated, on the same 

 authorities, that there are only two species in each case common to either Colwell 

 Bay, or Headon Hill and Brockenhurst, and not occurring at Barton ; while there are 

 twenty-six species common to Colwell Bay and Headon Hill, and not occurring at 

 Brockenhurst. It is clear, therefore, from all fossil and physical or stratigi-aphical 

 evidence, that the position of the Brockenhurst bed has been misconceived ; and 

 it would be fatal to re-name the whole series of strata hitherto so well known 

 and well determined as the Middle Marine or Middle Headon, of the Isle of Wight, 

 and call it the * Brockenhurst series.' The classification and nomenclature of the 

 Geological Survey must therefore be restored and maintained, all recent examination 



