( 21 ) 



DIVISION VI. SPIRULACEJE. 



4. Spirula. (1) Lam. 



The turns of the spire 

 not touching ; divided 

 transversally into cham- 

 bers. PL l,"fig 18. 



2. Spiaolinitis. Lam. 



The turns of the spire 

 touching; the septa pro- 

 jecting in a small degree, 

 so as to divide the exterior 

 surface of the spire by 

 crests or striae. PL 1, fig. 

 13. 



GENERA. 



Siphon occupying the Austral Seas. Gtilph 

 middle of each chamber of Florida. V. Animal, 

 and continued to the ex- p. 54. 

 tremity of the shell. 



Siphon traversing the 

 septa and chambers. 



Grignoh. (2) 



3. Ammonoceratites. (3) 

 Lam. 



Septa numerous., undu- 

 lated at the margins. PL 3, 

 fig. 14. 



Siphon marginal, in- Rolled on itself in the 

 terior. same plane ? 



(1) Peron's discovery of the animal of the Spirula, so nearly akin to the Nautili 

 that Linnaeus placed it amongst them, has thrown much light on all the multilocular 

 univalves : thitherto, it was a question whether the animal inhabited the last 

 chamber of the shell; whether it was contained entirely or partly within it; or 

 whether the shell was enveloped more or less completely by the animal. The 

 animal of the Spirula is perfectly analogous to the Sepia, and its shell is enchased 

 in the posterior extremity of the body, and only visible in part. There is now very 

 little, or no doubt, therefore, that the Rotalites, Belemnites, Hippurites, etc etc. 

 were more or less enchased in the posterior extremity of the animal, a portion of 

 whose body was enveloped in the last chamber and connected, probably, by a 

 tendinous fdament inserted at the extremity of the siphon, similar to tbat of the 

 Nautilus. Breynius, on the authority of Woodward (Catalogue of English Fossils. 

 Part I, p. 113 ), says, that the shells of the Spirula abound on the shores of Jamaica, 

 Barbadoes and the Bahamas : he adds, " de figura autem animalculi domicilium 

 hoc testaceum curiosissimum inhabitants, altum apud ornnes silentium." p. 22. 



(2) Lamarck has mentioned the genus Cristcltaria (PL 3, fig. 13), but without 

 defining it, and there are none in the Museum. These shells are cretaceous, and 

 almost microscopic. Fossil species, pyritous or ferruginous, are found in Tuscany ; 

 and M. Defrance possesses others, which are said to have been brought up with 

 the soundings olf Teneriffe. 



(3) The locality is unknown. M. Lamarck purchased it by accident : he kindly 

 allowed me to take it home, in order that the figure, which is the first that has been 

 made, might be as accurate as possible. 



