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 Cephalopoda, and consider as internal shells the 



Camerines, Brug. — Nummulites, Lam. 



Commonly called Nummidites\ Numesmalites, lenticular stones, &c. 

 which also are only found among fossils, and present, externally, a 

 lenticular figure without any apparent opening, and a spiral cavity 

 internally, divided by septa into nvunerous small chambers, but with- 

 out a siphon. It is one of the most universally diffused of all fossils, 

 forming, by itself 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 have only a single range of chambers in each 

 whorl;]:. 



Some very small species are also foimd in certain seas||. 



The margin of other small species, (the siderolit/ies,, Lam.,) 

 both fossil and living, are bristled with points which give them a 

 stellated appearance^. 



The labours and researches, fruits of an infinite imtience, 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, both in the sea, among the sand, 

 fucus, &c. and in a fossil state in the sand formations of various 

 countries. They vaiy in a remarkable degree as to their general 

 form, the number and relative position of the chambers, &c. In one 

 or two species, the only ones whose animals have been observed, there 

 appears to be a small oblong body crowned by numerous and red 

 tentacula, which, added to the septa of the sliell, have caused them to 

 be placed immediately after the Cephalopoda, like the genera just 

 mentioned, an arrangement, however, which requires to be confirmed 

 bv more numerous observations before we can consider it as conclusive. 



Such of these species as were kno^\^l in the time of Linnaeus and 

 Gmelin were placed by those naturalists among the Nautili. 



* Montf. Jouin. de Phys., an. VII. pi. i, f. 1. There are some doubts as to the 

 position of the siphon. Perhaps, as M. Adoiiin obsenes. what has been taken for 

 it, is the cohimellar conrohition. 



t The stone termed pierre de Laon is wholly formed of Nummulites. The 

 pyramids of Egrypt are placed upon rocks of this description, which also furnished 

 the materials of the superstructure. See the Memoir of Fortis on tjje Discolites in 

 his work on Italy, and that of M. Uericart de Thurij, as well as Lam., Anim. sans 

 Verteb., VIII, ami M. D'Orbigny, Tab. Method, des Cephalopodes. 



:J; Nautilus mammilla, Ficht., and Moll., VI, a, b, c, d ; — Naut. lenticularis, 

 VI, e, f, g, h, VII, a — h. To this genus also we refer the Licophre and EGEOXii, 

 Montf., 158, 166, and his Rotalite, 162, which differs from the Rotalies of 

 Lamarck. 



\\ Nautilus radlatus, Ficht. and Moll., VII., a, b, c, d ; — Naut. Venosus, lb., e, 

 f, g, h. 



§ Siderol. calcitrapo'ide, Lam. Fau., Mont, de St. Pierre, pi. xx.xiv, 



VOL. m. c 



