326 



central line drawn through the nucleus. If anything the fossil 

 shell is larger and more solid, although it must be stated, that, if 

 an immature fossil shell be selected for comparison with only the 

 same number of Avhorls developed as in the mature living form^ 

 the latter seems to be tlie broader of the two." 



14. Natiea pepspeetiva, s/hc. nor. pi. x., %. 7. 



Shell thin, globulai*, spire short, conic, somewhat obtuse ; 

 whorls four and a-half, narrow, ventricose, slightly depressed in 

 front of the suture ; suture linear imjDressed. Surface smooth, 

 shining, ornamented wdth striae of growth : obsoletely w-avy- 

 striated spirally, more conspicuous on base of body -whorl. Aper- 

 ture regularly semilunate, erect: outer lip thin : columella-margin 

 thin, thinly and freely everted' posteriorly, joined by a callous 

 film to the outer lip. Umbilicus broad, profund, simple, defined 

 by an obtuse keel confluent with the basal angle of tlie aperture 

 which is there thickened ; the columella-^\■all of the umbilicus is 

 somewhat concave, vertically and transversely lined. 



Dimensions. — Length, 17 : width, 16'5 : V)ase and radius of 

 aperture, 12-5 and 8 ; width on umbilicus, 4. 



Localities. — Eocene : Muddy Creek (common) ! ; Mornington! : 

 Gellibrand River I ; Camperdown ! ; Cheltenham I, Miocene: 

 Gippsland (one ex. !). 



Affijiities. — N'. perspecfira is related to ^V. limata, Imt it has 

 more convex w^horls, body-whorl much larger, larger umbilicus 

 defined by a keel ; from N. poJita it is separable by its globose 

 form, narrow suture, and wide umbilicus. Among exotic species 

 it has a near ally in N. semilunata, Lea, of the Alabama-Eocene 

 from which it ditters chiefly in its impressed suture. 



15. Natiea Aldingensis, ■•<pec. nor. PL x., fig. 5. 



Shell moderately solid, somewhat intermediate in shape be- 

 tween iV^. Jimata and X. perspectica, but with a shorter spire, and 

 though the suture is open yet it is not distinctly channelled as in 

 those species ; the umbilicus is like that of limafa, but is much 

 narrower. 



Surface ornamented with striie and lines of growth, the latter 

 raised into slight wrinkles at the suture, and obsolete spiral 

 lines and strise. 



From H. spinilunata it is distinguished by its more ventricose 

 spire-whorls and small umbilicus. 



Dime7isions. — Length, 19 : width, 18 : diameter and radius of 

 aperture 19 and 9-5 : width of umbilicus, 2-5. 



Localities.— 'EocEyE : Aldinga Clifts (common) : and Adelaide- 

 bore. 



