HEADON HILL AND COLWELL DAY IN THE ISLE OP WIGHT. 123 



at Brockenhurst it would have been found in Bracklesham beds 

 probably; we consider it a young example of T. infundibuliformis 

 (Lam.). We do not know why Edwards should have referred 

 Brockenhurst forms to a different species from the common Barton 

 species : we have compared numerous examples both from Brocken- 

 hurst and Whitecliff Bay, and consider them identical with Lamarck's 

 species ; we therefore rank T. obliqua as a synonym. 



Nerita cestuarina (Ed. MS.) seems identical with iV. zonula (S. 

 Wood). 



Neritina neritopsidea (Ed. MS.) is from the Upper Headon ; we 

 therefore omit it. 



Ostrea flabelhda (Lam.) is in Edw. coll. labelled as from " Col- 

 well Bay or Headon Hill 99 [sic], but in error ; the specimen has 

 evidently come from the Barton Clay. 0. ventilabriim is not in 

 Edw. coll. from Colwell Bay, and it does not occur there ; we are 

 not sure that the distinctive differences given by Mr. Searles Wood 

 between this species and 0. flabelhda are constant ; we have com- 

 pared examples of this oyster, so common in the Brockenhurst bed 

 at Whitecliff Bay, with other examples from Barton beds ; and 

 some we consider perfectly identical with Barton and Bracklesham 

 forms. 



Avicida media (Sow.) is not in Edw. coll. as from Hordwell or 

 Headon Hill, but from Long Mead End, i. e. probably from the 

 Beacon Bunny (Barton) beds. 



Dreissena Brardii (Eauj.) is in Edw. coll. from Hamstead and 

 Hordwell (Long Mead End), ranging thus through all the fresh- 

 water series. It occurs in social groups. We found a single derived 

 specimen just above the Lower-Headon boundary at Whitecliff Bay. 



Anomia tenuistriata (Desh.) is in Edw. coll. labelled as from 

 Barton, Brockenhurst, and Hordwell ; if the Brockenhurst example 

 is to be identified with A. Alcestiana (Nyst), probably the Barton 

 ones are so also. We follow Edwards in considering them all one 

 species. 



Mytilus strigillatus (Wood) in Edw. coll. is only from Barton 

 beds ; we therefore omit it. M. affinis is abundant at Colwell Bay, 

 and ranges up from Barton beds. 



Nueula similis (Sow.) is in Edw. coll. only from Barton beds ; we 

 found one imperfect specimen, however, at White Cliff Bay in the 

 Brockenhurst bed. N. lissa (S. Wood) is said by Mr. Wood to occur 

 at Brockenhurst ; but it is not in Edw. coll. as from there ; the 

 Hordwell examples are possibly from the Upper Bagshot Sands. 



Area appendieulata (Sow.) and A. laevigata (Caill.) are in Edw. 

 coll. as from Barton and Bracklesham beds. 



Cardita deltoidea (Sow.) is not in Edw. coll. from Colwell Bay ; 

 and we doubt the fact of its occurring there. 



Lucina Menardi (Desh.), as so determined, is not in Edw. coll. 

 L. gibbosula (Lam.) and L. pratensis (Ed. MS.), in Edw. coll. as 

 from Long Mead End, are not from Headon beds : we therefore 

 omit them. L. obesa (Ed. MS.) and L. inflate (Ed. MS.) are in 

 Eclw. coll. as from Barton beds ; the former is not distinguishable 



