CEPHALOPODA. 45 



No. 7. Nautilus centralis. Sotoerby. Tab. Ill, fig. \a — c. 



Nautili s CENTRALIS. J. Sow. 1812. Min. Con. vol. i, p. 11, tab. 1, left-hand figure. 



— australis (by error for centralis). Befrance. 1825. Diet, des Sc. Nat. vol. xxxiv, 



p. 297. 



— centralis. Wetherell. 1836. Philos. Mag. and Journal, vol. ix, p. 465. 



— Bvcklandi. (?) Michelotti. 1840. Ind. rag. di alcuni Testacei de Cefal. foss. &c. 



Aun. delle Scien. del Regno Lomb.-Veneto, p. 4. 



— centralis. Morris. 1843. Cat. Brit. Foss. p. 182. 



— — Pictet. 1845. Traite" element, de Pal6ont. vol. ii, p. 338. 



_ _ Sow. 1849. Dixon's Geol. Hist. &c. pp. 110, 121, tab. 14, fig. 28. 



N. testa globosd, in aspectu ventrali rotundatd ; aperturd semilunari ; nmbilicatd, 

 umbilicis angustis, profundis ; septis extus concavis, simplicissimis, siphone centrali, 

 minimo, continuo perforatis ; lobis dorsalibus latis, hand reflexis. 



The N. centralis, in the simplicity of the septa and the central position of the 

 siphuncle, nearly resembles the recent Nautili. It is a very ventricosc, almost a 

 globose shell, much rounded on the ventral aspect ; the aperture is bluntly lunate, 

 nearly semicircular, and is rather more than twice as wide as it is long ; the open 

 umbilicus is narrow and deep ; the septa are concave outwardly, and simple, scarcely 

 presenting any undulation or second curvature whatever ; the dorsal lobes are broad, 

 each being nearly one third of the width of the aperture, and they are bluntly rounded 

 on their superior margins ; the siphuncle is very small, central, or nearly so, and 

 continuous. The lines of growth present broad undulations, and are strongly marked 

 and decussated. 



Michelotti has described a Nautilus from the Miocene formations of the Colle de 

 Torino, in Piedmont, to which he has given the name Bucklandi. He quotes 

 N. centralis of Sowerby by the name N. australis (an error into which he has fallen by 

 relying on Defrance's quotation), and he considers his shell to be identical with it, 

 and, oddly enough, associates with it N. imperialis. The specific description given by 

 this author agrees tolerably well with that of the present species ; but I have nol 

 myself had any opportunity of comparing the Piedmontese with the English shell ; and 

 as Michelotti does not mention his having compared the two, and he appears to have 

 trusted implicitly to Defrance, the accuracy of the identification must for the present 

 be considered as doubtful. 



Mr. Wetherell, in his paper above quoted, gives this species and Naut. regalis as 

 characteristic of the middle division of the three which he thinks might be made of 

 the true London Clay. It occurs at Regent's Park, Chalk Farm, Hyde Park, Richmond, 

 Sheppy, and Bognor ; it is also found, though very rarely, at Bracklesham Bay. 



The species does not appear to have attained a great size, the largest specimen not 

 exceeding 3' 7 in. in diameter, by 3'3 in. across. The figs. 1 and 2, Tab. Ill, are taken 

 from specimens in the collection of Mr. Wetherell ; fig. 3, from one in that of Mr. 

 Sowerby. The form of the septum is shown by fig. 2, Tab. VIII. 



