CEPHALOPODA. 17 
in the same plane, suddenly descend, giving’ to the shell that form of 
an obelisk which is called turreted.* * * § 
It is also thought, and from similar considerations, that we should 
refer to the Ceijlialopoda, and consider as internal shells the 
Caa[erines, Brug. — Nummulites, Lam. 
Commonly called Nam/nulites, Numesynalites, lenticular stones, &c. 
which also are only found among fossils, and present, externally, a 
lenticular figure without any apparent opening, and a spiral ca-vnty 
internally, divided by septa into numeroiis small chambers, but with- 
out a siphon. It is one of the most universally dift’used of all fossils, 
forming, by itselt alone, entire chains of calcareous hills and immense 
bodies of building stonef. 
The most common, and those which attain the greatest size, form a 
complete disk, and liavc only a single range of chambers -in each 
whorl|'. 
Some very small species are also found in certain seas|(. 
The margin of other small species, (the siderolithes,, Lam.,) 
both fossil and living, are bristled with points which give them a 
stellated appearance^. 
The labours and researches, fruits of an infinite patience, of Bian- 
chi (or Janus Plancus), Soldani, Fichtel, and Moll, Ale, and D’Or- 
bigny, have ascertained an astonishing number of these chambered 
shells without a siphon, like the Nummulites, that are extremely 
small and frequently microscopical, l)oth in the sea, among the sand, 
fucus, &c. and in a fossil state in tlie sand formations of various 
countries. They vary in a remarkable degree as to their general 
form, the number and relative position of the chambers, &c. In one 
or two species, tlie only ones whose animals have been observed, thei’e 
appears to be a small oblong body crowned by numerous and red 
tentacula, which, added to the septa of the shell, have caused them to 
Ije placed immediately after the Cephalopoda, like the genera just 
mentioned, an arrangement, however, which inquires to be confirmed 
l)y more numerous observations before we can consider it as conclusive. 
Such of these species as were known in the time of Linnaeiis and 
Gmeliu were placed by those naturalists among the Nautili. 
* Montf. Journ. de Fliys., an. \'I1. pi. i, f. 1. There are some doubts as to the 
position of the siphon. Perhaps,- as M. Adouin observes, vvhat has been taken for 
it, is the columellar convolution. 
'i' The stone termed pierre de Laon is wholly formed of ’Nummulites. The 
pyramids of Egypt are placed upon rocks of this description, which also furnished 
the materials of the superstructure. See the Memoir of Fortis on the DiscoHtes in 
his work on Italy, and that of M. Hericart de Thuvij, as well as Lam., Anim. sans 
Verfeh., YIIl, and M. D’Drbigny, Tab. Method, des Cephalopodes. 
Nautilus mammilla, Ficlit., and Moll., VI, a, b, c, d ; — Nuuf. lenficularis, 
VI, e, f, g, h, VII, a — h. To this genus also we refer the Licophrb and Egeonk, 
Montf., 158, 166, and his Rotalite, 162, which differs from the Rotai.ies of 
Lamarck. 
II Nautilus radiulus, Ficht. and Moll., VII., a, b, c, d ; — Naut. Venusus, Ib., e, 
f, g, h. 
§ Siderol. calcitrupo'ide, Lam. Fau., jMont. de St. Pierre, pi. .\xxiv. 
VOL. III. 
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