NOTES ON THE CAMBRIDGE GREENSAND. 497
tion of the several specimens proved this surmise to be correct, Mr. Seeley's types answering exactly to the middle and upper por- tions of the Gault specimen, which also possessed the angulated body- whorl of the other Cambridge casts.
The shell was consequently described by Mr. Gardner under the generic name of Brachy stoma, and its affinities with the Aporrhaidse duly pointed out.
Chemnitzia tentjistriata.
Cerlihlum tenuistr latum, Seeley, Ann. & Mag. Nat. Hist. 1861, vol. vii. pi. xi. fig. 6.
Pyrgiscus tenulstrlatus, Gardner, Geol. Mag. dec. 2, vol. iii. p. 112.
In his valuable paper on Cretaceous Gasteropoda above referred to, Mr. Gardner describes some scalariform shells similar to the C. tenulstr latum of Mr. Seeley, referring them all to Philippi's genus Pyrgiscus, and deprecating at the same time the union of such forms with the genus Chemnltzla.
The reason which he gives for the revival of this genus, viz. the want of columellar plaits, can hardly be regarded as sufficient, especially as I find on referring to the ' Enum. Molluscorum Siciliae,' vol. ii. p. 136/ that Philippi himself acknowledged its identity with the Chemnltzla of D'Orbigny.
It is difficult to understand why palaeontologists have ignored the existence of the latter genus in Cretaceous rocks, when it is recorded from Jurassic beds, and known in Tertiary and Recent times ; and I cannot help thinking that many of the so-called Scalarlce are in reality Chemnltzla?.
Mr. Gardner's own description of Pyrgiscus is almost identical with that of Chemnltzla in Woodward's ' Manual of the Mollusca,' p. 239 ; and it essentially differs from Scalarla in the form of the mouth, and by its incomplete peristome.
It is remarkable that the two other species described by Mr. Gardner are from the Folkestone Gault and the Blackdown beds respectively; they are certainly all very closely related, and may, I think, turn out to be varieties of the same form when more specimens come to be compared.
Turbo Pictetiantts, D'Orb. PL XXI. figs. 3-5.
Turbo Plctetlanus, D'Orb. Pal. Fr. vol. ii. pi. clxxxiv. figs. 8-10 ; Pict. & Roux, Gres Verts, pi. xix. fig. 1.
Turboldea nodosa, Seeley, Ann. & Mag. Nat. Hist. ser. 3, vol. vii. p. 289, pi. xi. fig. 14.
The figures of Turbo Plctetlanus, both in D'Orbigny and Pictet & Roux, fail to give an adequate idea of this shell ; and if Mr. Seeley had never seen specimens he may be forgiven for not having recognized the identity of the Cambridge fossil with the Perte-du- Rhone form.
Specimens now in the Woodwardian Museum, however, leave no
