74 
edge of the preceding whorl, and this chamber, being 
closed by a convex septum without any continuing mar- 
gin, is not readily distinguishable in species which have 
very small chambers in proportion to their diameter, as 
most of the established Nummulites have : this and the 
ordinary imperfection of the specimens have together 
misled Authors ; it is a character easily traced in Len- 
ticulites planulata. 
The Nummulariae are supposed to belong to the same 
division of the Order Cephalopoda as Nautilus, Spirula, 
&c. It is considered, with much probability, that they 
were enveloped entirely by their animals, because they 
have no large chamber for their lodgement. Several if 
not all the genera of minute chambered shells have pro- 
bably been similarly situated, and agree also in the want 
of the siphuncle and in having convex septa. Hence 
they will form a natural group, near to, but distinct from, 
Nautilus, Belemnites, &c. 
Nummulites were by the ancients thought to be pe- 
trified lentils. A species found in Egypt near some of 
the pyramids is so spoken of by Strabo. Several species 
are apparently united by Gmelin under the genus Nau- 
tilus, with the specific name Helicites (page 3371), which 
is given to them by Guettard. Bruguieres named the 
genus Camerina (Enel. Methodique) ; but Lamarck has 
justly retained the old name. We adopt Nummularia in 
preference to Nummulites because some of the species 
we include are recent. 
Nautilus Comptoni, tab. 121, belongs to this genus. 
