STRATA OF THE HAMPSHIRE BASCT. 159 



Mya donacialis, Edw. MS. 

 Corbula vectensis, Forbes. 



subpisum, d' Orb. 



Panopaea Heberti, Bosq^. (P. miuor, Forbes). 

 Pholas, sp. 



If we now turn our attention to the forms of life contained in 

 the two groups of freshwater and estuarine strata alternating with 

 the three marine series which we have indicated, the views at which 

 we have arrived concerning the age and foreign equivalents of the 

 latter are supported and strengthened. The lowest of these groups 

 of freshwater and estuarine heds is more than 400 feet in thickness, 

 and exhibits many indications of the prevalence from time to time 

 of brackish-water and marine conditions. Hence there have been 

 collected from these beds a considerable number of marine forms, in 

 all about 100 species. Now if we examine their distribution, we 

 arrive at some interesting results. About one half of them occur in 

 the Brockenhurst series above, one third in the Barton below, while 

 one third are peculiar, and one sixth common to all three formations. 



If we compare the British with foreign deposits, we find that the 

 marine fossils of this lower group of estuarine strata agree very 

 closely indeed with those of the series of beds developed at many 

 points of the Paris basin, as at Mortefontaine, Senlis, and Monneville, 

 and now well known to geologists under the name of the " Zone of 

 Ceritliium concavum,'' Sow. (" Sous-etage de Mortefontaine " of C. 

 Mayer). 



Marine Fossils from the BraclcisJi-iuater Bands of Headon Hill and 



HordweU Cliffs. 

 \a Pass up into the Brockenhurst series, x Pass down to the Barton clay.] 



a Marginella simplex, Edw. 



vittata, Edw. 



a Pleurotoma headonensis, Edw. 



a denticulata, Bast., var. odontella, Edw, 



Woodi, Edw. 



a, X Borsonia sulcata, Eouault. 

 a, X Eimella rimosa, Sol. 

 a, X Hippocrenes (Rostellaria) ampla. Sow. 

 a Murex sexdentatus, Sow. 



Fasciolaria crebrilinea, Edw. MS. 



Pisania (Fusus) scalaroides, Lam. 

 a Natica grossiuscula, Edw., MS. 



Studeri, Brown, yar. clausa, Edw. 



a, X labellata, Lam. 



X Odostomia hordeola, Lam. 



Ob loxodonta, Edw. MS. 



a subumbilicata, Edw. MS. 



a geminata, Edw. MS. 



a multispirata, Edw. MS. 



a gracilis, Edw. MS. 



X Turbonilla obliquecostata, Edw. MS. 



sorella, Edw. MS. 



a Scalaria laevis, Morr. 



Cerithium concavum, Sow. 



gyrostoma, Edw. 



