4.40 CRETACEOUS GASTROPODA 
have the fissure non-symmetrically ventral, being placed somewhat laterally to the 
left; but as there are as yet no other noticeable distinctions between the typical 
shells of this genus to be given, it does not appear necessary to make a further 
separation into genera or sub-genera. I am not aware whether any recent species 
of Fustiaria have been described, but I have little doubt that when the animal has 
been observed, it will be found to exhibit equally marked distinctions from that of 
Fntalis as does the shell. 
b. Sub-family,—GADILINA. 
This sub-family ought principally to include the species called by Sars Sipho- 
nodentalium, the animals of which have a very long cylindrical foot, ending in a 
ciliated, flat or conical disk, the lips of the aperture have no appendages, and the 
liver is unsymmetrical. 
The shells in general resemble those of the avrazzy#, but as they appear 
usually to inhabit deep waters they always consist of a thin substance; the posterior 
end is generally less pointed and more widely opened than in the previous sub- 
family. 
5. Siphonodentalium, Sars, 1859 (Om Siphonodentalium vitreum, etc., Univer- 
sitets-Program, Christiania, 1861). Shell tubular, tapering posteriorly, being occa- 
sionally cylindrical or even somewhat contracted anteriorly, aperture circular with 
entire margins, posterior end with the margin lobed. 
The genus Siphonodentaliwm must be restricted to species of the type Siph. 
vitreum, Sars, that is, to those forms which have the margin at the posterior termina- 
tion of the shell lobed. In Siph. vitreum there are six short fissures all round 
the margin, but of these the dorsal and ventral ones appear to be slightly longer, or 
deeper, than the other four. Beside this recent species I am acquainted with three 
fossil ones, lately described by Deshayes as Gadus parisiensis, G. bilabiatus and 
G. brevis (Paris fossils, 2nd edit., pp. 218-219, etc.) ; all three species have the pos- 
terior margin symmetrically and on both sides distinctly fissured, in the first species 
the rest of the margin being numerously but less deeply indented, while in the two 
others it is not indented at all. It is not improbable that further investigations may 
render it desirable to divide this genus into different sections or sub-genera, but 
until more species* of these shells are known and more animals have been examined, 
the limit of these sub-generic groups could not be ascertained, nor do they appear 
necessary at present. Chenu in his “Illustrations Conchil.” (pl. 6, fig. 31) gives 
a figure of a Dentalium turritum, Lea, which closely resembles Siphonodentalium 
vitreum, only having the shell a little thicker. Lea (Contr., p. 35) says that there 
are at the posterior end only four appendages, not six, as in the recent species ; 
Siph. turritum was found in the eocene beds of Alabama. I also may mention 
that the names of the two species Siph. parisiense and 8. bilabiatum of Deshayes 
have to be replaced by Siph. denticulatum and 8. bifissuratum respectively, the same 
* One species was described by Searles Wood in the Annals Mag. nat. hist. af 1842. 
