Victor tan Fo.ssUs, Part XVTf. 355 



Casts of tlie interior of the shell of this species, from the Murray 

 River cliffs, show that the annular lobe on the dorsum or impressed 

 zone is very distinct in the earlier camerae, but become fainter, 

 and disappear on reaching the ephebic stage of the shell. It is 

 interesting to note in connection with the presence of the annular 

 lobe in this species, that it is also seen in another Australian form, 

 N. felix, but less strongly developed. 



Dimensions. — The type specimen of N. geelo?i(/ensis, figured by 

 Foord (op. cit. p. 333, fig. 69), has a maximum diameter of about 

 114 mm. The heigFt of aperture is about 45 nmi., and the width 

 63 mm. 



A shell from Fyansford shows, height of aperture from impressed 

 zone to periphery, 25 mm. ; width, 32 mm. 



Another specimen (cast), from the Murray River, measures on 

 the aperture about 67 mm. in height, and 89 mm. in width. 



Observations.- — This species is apparently the commonest and 

 best known of the Victorian Tertiary nautili, since it is a typical 

 form in the widely developed Janjukian series, although ranging into 

 the Kalimnan. Occurring so often in polyzoal rock, however, it is 

 met with generally in the form of an internal cast of the shell. 

 This is obviously due to the great solvent processes continually pro- 

 ceeding in and through this porous limestone. The characters and 

 form of the original shell are so often clearly shown in the casts, as 

 to leave no room for doubting the identity of the species. The 

 general form of N. geelongensis is like that of N. imperiolis, 

 Sowerby,! but is not so wide at the aperture. 



Occurrence and Horizon. — The original locality, " near Gee- 

 long," is somewhat vague, as it may have come from any of the 

 chalky or polyzoal limestones within a wide radius in that district. 

 All of those localities, however, would belong to the Janjukian 

 series. Casts of Nautilus, probably of this species, occur in South 

 Australia, in the Avhite and yellow limestone of the Murray cliffs. 

 A cast of N . geelongensis preserved in the white polyzoal lime- 

 stone of that locality Avas presented by the late Rev. C. S. Y. Price, 

 to whom the Museum has been indebted from time to time for many 

 valuable specimens. 



The small example, having the shell preserved, was collected by 

 Mr. J. F. Mulder, at Fyansford, the deposit at which locality I 

 now include in the Janjukian series. 



1 Min. Conch., vol. i., 1812, p. !), pi. i. 



