18S 
THE LIAS AMMONITES. 
Harpoceras serpentinnm, Scldotheim (fig. 54). 
— radians, Reinecke. 
— bitVons, Bniguiere. 
Harpoceras insigne, Schilhler. 
— thouarsense, d'' Orhigvy. 
opulimini, Iteinecke. 
III. Amalthei. — The sickle vanishes, the radii have a very long stem, which bends 
only near the siphonal area, becoming here very prominent. The 
margin is sharp, the keel often divided by the folds as if into scales. 
The siphonal lobe is here also much shorter than the upper lateral, 
and its wall ascends obliquely up to the siphonal saddle, but not 
by any means so obliquely as hi the Falciferi. The upper lateral 
is very broad, almost as broad as it is deep, so also is the under 
lateral. The saddles, as well as the lobes, are extensively foliated, 
so that in these lobes large and wide outstretched processes are 
formed in the middle of the saddles, with very deep secondary 
lobes. The points of the dentations do not hang down, but in 
general stand perpendicularly upon the axis of the lobes. By this means the sides of 
Amaltlieus in all the species, even when the shell is wanting, have an especially foliated, 
incised appearance, in which great intricacy appears to prevail. Notwithstanding, with 
some attention we easily, even to the least detail, find the ever-repeated symmetry as well 
in the individual points as in both sides of the wdiorls. These Ammonites are much 
inclined to become involute. The family ascends from the Lias up to the Coralline 
Limestone of the Middle Oolite, and each intermediate formation possesses its oAvn 
special forms. The following are typical species from the Lias and Coral rag. 
Fig. 55. — Amaltheus cordalus, 
Sow. 
Amaltheus margaritatus, Mont fort. 
— Guibalianus, cT Orbigny. 
— Greenhoughi, Sowerby. 
A.aialtlieus oxynotus, Quenstedt. 
— spinatus, Bruguiere. 
— cordatus, Sowerby (fig. o.^i). 
IV. Capricornx — This group connects itself very closely with the Amalthei. 
Erom Amaltheus margaritatus, through Amal. cordatus, Amal. Lamberti, and AmaJ. 
ODijjhaloides, we arrive at Aeg. ca^nicomum. The scales upon the keel of these 
Ammonites have even raised themselves higher, and are first bent 
forward, then become broad folds with a point before. Ihe siphonal 
area of the Capricorni is broad, often broader than the sides. The 
siphuncle is not specially prominent, the ribbing of the folds 
on the sides is in general unusually strong, always single, even on 
the back ; without much flexion, and rarely with knobs or spines 
upon the sides. The siphonal lobe in general goes out perpen- 
dicular with vertical walls. The lateral lobes are, as in the 
Amalthei, less deep than broad, and often at their bases are 
broader than at the mouth, they are all very slightly or almost not 
at all involute. The following species are typical forms. 
Fig. 56. — Aegoccras capri- 
cornwn, Sclilotli. 
