Arkell.1956.Jurassic..

2 10 ITALY AND CORSICA
figured in a long series of monographs by Fucini (1919, 1920-35). Despite
this thorough systematic work, however, much remains to be done to
determine the stratigraphic range of the species and genera. Even the
boundary between Domerian and Toarcian is in doubt; for all the fauna
figured by Gemmellaro (1885) as of the Upper Lias is Domerian, while
many of the Dactylioceratidae figured by Fucini (1935) as Domerian seem
to be Toarcian. Unfortunately also, Fucini employed a taxonomic scale
out of harmony with that of all other palaeontologists except Buckman,
and a number of his genera represent no more than species; further, he
erected many new genera without diagnosis or type species, so that it is
difficult to determine which are valid nomenclaturally (see Vecchia, 1949;
Haas, 1947; 1951). Fucini's plates suggest that these Sicilian faunas
have a strong local element, but work by Dubar in Morocco and by
Mouterde in Portugal has thrown important light on these successions.
LOWER PLIENSBACHIAN
The best-known fauna of this age is from the beds with 'Terebratula'
aspasia at Rocce Rosse, near Galati, in the province of Messina. The
beds consist of compact grey limestone interbedded with marls and silts.
They yield many Phylloceratids, especially Juraphyllitids, including the
type-species of Juraphyllites (Rhacophyllites diopsis Gem.) and of Galaticeras
('Amphiceras' harpoceraides Gem.), with interesting Polymorphitids,
including the type species of Gemmellaroceras ('Aegoceras' aenigmaticum
Gem.), with Tropidoceras, Eoderoceras, Lytoceratids and other genera
(Gemmellaro, 1884). In the province of Palermo and probably elsewhere
the so-called Terebratula (or Pygope) aspasia beds are later, Upper Pliensbachian,
as shown by the ammonites figured (Gemmellaro, 1872-82,
p. 53, pis. x-xii).
SINEMURIAN AND HETTANGIAN
These stages probably exist in most parts of the island except perhaps
in the west, where it is difficult to separate them from the Trias. In the
extreme east and extreme west they are represented by semi-crystalline
limestones ranging in colour from black to white and often crowded with
a neritic fauna of gastropods, pelecypods and brachiopods. They are
best dated at Monte Casale (Rocca Busambra), province of Palermo,
whence a wonderful fauna has been figured from a white marble-like
crystalline limestone (Gemmellaro, 1872-82, p. 233 ff., pis. xxi-xxxi;
gastropods revised by Fucini, 1913, which see for references to works on
other groups). The ammonites (Gugenberger, 1936) represent the whole
of the Hettangian and Sinemurian, from the Planorbis Zone to the
Raricostatum Zone. Of 65 species recognized, Phylloceratids are in a
large majority, both in species and individuals (43 per cent., 47 per cent.),
followed by Lytoceratids (21 per cent., 20 per cent.) and Arietitids (20 per
cent., 17 per cent.). The remainder includes Schlotheimiids, Psiloceratids,
Eoderoceratids, and Tethyan Lytoceratina such as Ectocentrites, Pleuro-
http://jurassic.ru/