RISSOINA. 275 
The late Professor Eugéne Deslongchamps (‘ Notes Paléontologiques,’ vol. ii, 
May, 1889, p. 70) could not be persuaded that Amberleya and Hucyclus were 
synonymous, and thus he maintained that Amberleya nodosa, M. and L., could not 
be a Hucyclus. The presence in that species of a slight umbilical excavation 
was one of his principal reasons for considering that Amberleya and Hucyclus are 
distinct genera. As so often happens, Amberleya nodosa, the type, is far from 
being a typical species, and it would have been far more satisfactory if Turbo 
ornatus, Sow., could be taken for the type, as was done by Deslongchamps in 
constituting his genus Hucyclus. 
With regard to the relationship of Amberleya, some authors, like Fischer, 
admit that the various forms grouped under this genus have the appearance of 
Tectarius, Echinella, and Littorina; but Fischer considers that the alleged 
existence of a nacreous layer in the Jurassic Amberleyas proves their affinity 
with the Turbinide and the Trochide. Of course, if this is the case, the group 
of small shells which appear to be connected by so many links with Amberleya are 
wrongly named Littorina ; and that is why, as already stated, this term is only 
used in a conventional sense. It would save trouble if they were replaced under 
Turbo; and yet they certainly are not Turbos in the modern restricted sense, 
although they may belong to the Turbinide. 
Many of the forms described in the sequel seem to run into each other. 
Moreover some of the species differ so much at different stages of their growth, 
especially in the character of the aperture, that one and the same species might 
well be placed under two distinct genera. (See description of Amberleya ornata.) 
As regards arrangement, exception might be taken to the wide extension of 
the term Amberleya adopted in the subjoined classification of Inferior Oolite 
species. Unless we fall back upon Turbo and Trochus, I do not see how this is to 
be avoided. The distinction also between Amberleya and ‘ Littorina” is 
admittedly not a very philosophic one. 
If we attempt to deal with the Amberleya-Littorina group in sections, the first 
and most important section is that (1) of Hucyclus, where the shell is much 
turrited, the suture wide, the body-whorl ventricose, and one or more of the 
spiral belts exceedingly prominent. The Trochus-section (2) contains shells more 
or less trochiform, but with an ornamentation closely resembling that of 
Eucyclus. Through the more turbinate and finely ornamented forms of the 
Eucyclus-section, such as Amberleya densinodosa, a connection is established with 
(3) the Turbo-section, which presents some extreme forms. The shells of all 
three sections are rather thin, and exhibit a considerable resemblance in the 
general style of ornamentation, and frequently also in the changing character of 
the aperture. 
In the fourth section (4) the shells are thicker, but do not attain to any 
