AMMONOCERAS. 3 
genera Rostellaria, Pterocera and Strombus, to which would be 
added, Hippochrenes, Montf. and Apporrhais,Petiver. The shells 
of this family are distinguished by the spreading of the outer lip. 
ALA’TED. (From Ala, a wing.) Winged, a term applied to shells 
when any portion of them is spread out in any direction as in 
fig. 403. Hippochrenes, Montf. and Unio Alatus, fig. 147. 
ALEC’TRION. Montf. Buccinum Papilloswm. Auct. fig. 422. 
ALVEOLINA D’Orb. A genus of microscopic Foraminifera, 
AMAL'THUS. Montf. A. Margaritaceus, Montf. Is a species of 
AmmoniTE, described as very flat, keeled, with an angular aper- 
ture. Fam. Ammonacées, Lam. 
AMBIGUZ. Lam. The fourth section of the order Conchifera 
Dimyaria. Containing the family of Camacea, fig. 153 to 155. 
AMIMO'NUS. Montf. Conirres Ungulatus, Knorr. A species 
shghtly curved. Fam. Orthocerata, Lam. 
AMMONA'CEA. BI. The fourth family of the order Polythala- 
mia, Bl. or chambered shells, including the genera Discorbites, 
Scaphites, Ammonites and Simplegas, distinguished. from his 
Nautilacea, by the whorls being visible. 
AMMONACEA. Lam. Theseventh family of Polythalamous 
Cephalopoda, Lam. containing the genera Ammonites, Orbuli- 
tes, Ammonoceras, Turrilites, and Baculites, to which may be 
added Amalthus, Simplegas, Ellipsolites, Nautellipsites, Hamites, 
Icthyosarcolites, and other genera mentioned in the list of fig. 
477 to 484. 
AMMONITES. Auct.(from Jupiter Ammon) Fam. Ammonacées, 
Lam.& Bl. Descr. Symmetrical, convolute, discoidal, orbicular: 
chambers numerous, divided by lobate or sinuous septa, per- 
forated by a siphon: aperture generally more or less modified by 
the last whorl. The fossils of the secondary strata which compose 
this genus are numerous and well known, they are vulgarly 
called snake-stones, and some of them are very beautiful, particu- 
larly when the internal structure is exhibited by a section. 
There is some difficulty in distinguishing them from the fossil 
Nautili, for although the whorls being visible, and the septa sinuous 
may be taken as the characteristics of Ammonites, yet there 
are several species which partake of the characters of both. 
The Orbulites of Lamarck, for instance, have sinous septa like 
Ammonites, but the last whorl covers the preceding ones as in 
Nautilus. Simplegas of Montf. and Bl. has whorls visible ex- 
ternally and simple septa. Ammonites, fig. 478. 
AMMONOCE'RAS. 
AMMONOCE'RATITES. 
horn.) The shells described under this Lamarckian genus present 
an anomaly, which Sowerby considers merely accidental; they 
resemble the Ammonites in internal structure, but instead of being 
spirally convolute they are merely curved likeahorn. Ez, Fig. 
477, copied from Blainville. 
\Lam, (From Ammon, and Kepas, ceras, 
