618 MESSES. GAEDNEE, KEEPrN-G, AJ^D MONCKTON ON THE 



The preceding list contains 52 species of IToRusca f, for the col- 

 lection of which we are largely indebted to Mr. Herries. Of these, 

 43 could be determined specifically, 9 generically only, and there 

 was a considerable residuum which we were unable to identify. 

 Thirty-one are common to the Upper Bracklesham and Barton, only 

 3 are absolutely unknown in the Barton, and there are 9 Barton 

 species unknown in the Bracklesham. "We must not attach undue 

 importance to these, however, because a considerable distance sepa- 

 rates Barton from Tunnel Hill ; and we see that as far off as the 

 Paris basin, many of what are our most distinctive Barton shells in 

 Hampshire, such as Volvaria acutiuscula, Strombus hartonensis^ Sola- 

 rium j)licatum, become distinctive of the Calcaire Grossier, and are 

 quite unknown in the Sables lloyens, where we should expect to 

 find them. On the other hand, we may instance Dentalium grancle as 

 a purely Bracklesham species in Hampshire, ranging into the Sables 

 Moyens in the Paris area. If we take the * species, which are the 

 most typical and abundant, we find that only 4 of those common 

 to the two formations are more at home in the Bracklesham than 

 in the Barton, while the reverse is the case with no less than 28. 

 Though more of the Barton species belong to the Lower than to either 

 the Jy^iddle or Upper divisions of the formation, the Lower Barton 

 facies is not so apparent as we should expect it to be, probably 

 because the sandy bottom favoured species which could not exist in 

 the muddy bottom of the Hampshire basin. Making allowance for 

 this the palseontological evidence agrees with the stratigraphy, the 

 presence of the few Bracklesham forms leading us to place the Tunnel- 

 Hill horizon a little below that of High cliff. 



The Baeton Fauna. 



The fauna of the Barton Series is the richest in our Eocene, and 

 contains probably more species than have ever before been met with 

 in a single locality. The si^lendid preservation of the fossils and 

 their striking character attracted attention in very early times, and 

 the work by Brander in 1766 is one of the very earliest in which a 

 large series of fossils was accurately figured and described. They 

 seem to have been collected assiduously ever since, the recurring 

 wash of the waves against the base of the cliffs exposing fresh 

 specimens with every tide, whilst new crops of these delicate fossils 

 seem sprinkled over the dark slopes between Highchff and Hordwell 

 after every shower. 



Prof. Prestwich was able to enumerate 209 species from Barton in 

 his first paper, and in his second the number was increased to 301;^, 



t Only 15 forros are given in the Survey list, in the " Geology of the London 

 Basin," p. 600 ; and of these very few are determined specifically. At least 4 

 must be different from any in our list, 



X In 'Geology-,' vol. ii. p. 369, Prestwich says "The Barton day contains 

 310 species of Mollusca ' and 28 of corals; ^'■Nautili have not yet been met 

 with there.'' 



