274 GASTEROPODA OF THE INFERIOR OOLITE. 
Note.—Hitherto it has been possible for the most part to assign a family 
position to the genera of Gasteropoda occurring in the Inferior Oolite; but we 
now are called upon to consider several groups of shells, more or less turbinate 
in character, whose family position cannot with certainty be defined. The 
majority of these were referred to Turbo by d’Orbigny. 
The following genera are included in the above category, viz. Amberleya, 
* Littorina,” Cirrus (including Hamusina), and Straparollus (including Discoheliz). 
Preliminary Note on Amberleya and ‘* Littorina.” 
There is a twofold difficulty attendant on dealing with the numerous species 
of fossil shells which I propose to place under one or other of the above genera. 
To the uncertainty of family affinities there is also to be added the difficulty of 
synonymy. ‘The former is, of course, the more serious difficulty of the two; for 
if we are wrong in supposing that Amberleya, Hucyclus, &c., belong to the Littori- 
nid, in that case we are not justified in assigning the generic term “ Littorina” 
to the group of smaller species which are associated with them. The older 
writers, and particularly d’Orbigny, regarded nearly the whole of these forms as 
belonging to the Turbinide, and the modern tendency seems to be to revert to 
that conclusion. We may use Amberleya or Hucyclus without pledging ourselves 
to the family affinities of the genus, but if we use Littorina or Turbo the case is 
different. In the following pages “‘ Littorina”’ is used only in a conventional 
sense. 
In 1851, Morris and Lycett (‘Grt. Ool. Moll.,’ p. 54) thus diagnosed 
Amberleya :—* Shell turrited, turbinate, apex acute; whorls flattened above, 
convex and nodulated beneath, the last whorl ventricose ; aperture ovate, entire ; 
inner lip thickened and nearly covering a small umbilicus; sutures deeply 
impressed ; no columella.” 
The genus Hucyclus was constituted by J. A. Deslongchamps (‘ Bull. Soc. Lin. 
Norm.,’ vol. vy, p. 23 of separate copy) in 1860, being based on Turbo ornatus, 
Sowerby, and similar shells. The author alludes to <Aberleya (sic). He 
considered that genus to have been established on bad specimens, and to have been 
imperfectly characterised. His own diagnosis of Hucyclus is comprehensive 
enough,. It contains most of the points in the diagnosis which I offer below. 
There can be no doubt that Deslongchamps’ diagnosis was far more accurate 
and full than that of Morris and Lycett, which was little better than a description 
of one species. At the same time Deslongchamps, when he alluded to Amberleya, 
seems unconsciously to admit that his new genus might possibly be covered by 
that of the authors of the ‘ Great Oolite Mollusca.’ 
