CEPHALOPODA. 317 



Some very small species are also found in certain seas(l). 



The margin of other small species, (the Siderolithes, Lam.,,) 

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

 stellated appearance(2). 



The labours and researches, fruits of an infinite patience, of Bian- 

 chi (or Janus Plancus), Soldani, Fichtel, Moll, and D'Orbigny, have 

 ascertained an astonishing number of these chambered shells with- 

 out a siphon, like the Nummulites, that are extremely small and 

 frequently microscopical, both in the sea, among the sand, fucus. 

 Sec. and in a fossil state in the sand formations of various coun- 

 tries. They vary in a remarkable degree as to their general form, 

 the number and relative position of the chambers, 8cc. 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 shell, have caused them 

 to be placed immediately after the Cephalopoda, like the genera just 

 mentioned. This arrangement, however, requires to be confirmed 

 by more numerous observations before we can consider it as final. 



Such of these species as were known in the time of Linnaeus and 

 Gmelin were placed by those naturalists among the Nautili. 



M. D'Orbigny, who has exceeded every other person in attention 

 to this subject, forms them into an order which he calls Foramini- 

 FERA, on account of the only communication between the cells being 

 by means of holes, and divides them into families according to the 

 manner in which the cells are disposed. 



When the cells are simple and spirally arranged, they constitute 

 his Helicostega, which are again subdivided. If the whorls are 

 enveloped, as is particularly the case in the Nummulites, they be- 

 come his Helicostega Nautiloida(3). 



(1) Nautilus radiatus, Ficlit. and Moll., VII, a, b, c, d; Nauf. venosus, lb., e, 



(2) Siderol. calcitrapoide,'La.m., Fauj., Mont.de St Pierre, pi. xxxiv. 



(3) These infinitely sipall beings having but little to do with our plan, we will 

 merely cite the names of the genera with a few examples. The Nummulites 

 themselves are compressed in this first division under the name of Nummulines, 

 Nautilus pompiloides, Fich., and Moll., N. incrassatus, Id. 



The Stderolina, the same as the Sjderolites, Lam. 



Cristellaria, Nautilus cassis, Naut. galea. Id., &c. 



RoBULiNA, Nautilus calcar, Naut. vortex. Id. 



Spirolina, Spirolinites cylindraceu, Lam., Anim., sans verteb. 



Peneropla, Nautilus planatus. Fitch, and Moll,, &c. 



Dentritina, 



polistomella, 



Anomalina, 



