Palaeontology of the Older Tertia/ry. 333 



tends towards spiny elevations on the spiral threads under the 

 lens. The sranose ornament tends to become obsolete on the 

 flattened (in young specimens), to slightly convex base (in adult 

 specimens), but the young shells show several of the spiral threads 

 in the neighbourhood of the umbilicus with a fine beaded sculp- 

 ture. The ba'se of the adult shows about fourteen or fifteen 

 spiral threads, somewhat unequal, with an occasional fine inter- 

 calated thread near the periphery ; this spiral sculpture is 

 crossed by sigmoidal lines of growth radiating from the um- 

 bilicus. Base furnished with a wide and xeYj profound um- 

 bilicus extending nearly up to the embryonic whorls ; margin of 

 umbilicus furnished with a comparatively broad crenulated band, 

 while the whole interior bears beaded spiral threads of unequal 

 strength. Aperture quadrate, outer lip and inner lip both thin 

 and slightly crenulate in conformity with tlie spiral threads. 



Dimensions. — Height, 23 mm. ; greatest diameter, 29 mm. , 

 height of aperture, 7 mm. ; breadth of aperture, 9 mm. ; dia- 

 meter of umbilicus from margin to posterior of aperture, 9 mm. 

 More erect young forms, height, 18 mm. ; diameter at the base, 

 19 mm.; also 12 mm. by 10.5 mm.; 10 mm. by 10 mm., and 

 8 mm. by 8 mm. 



Locality. — Lower beads of Muddy Creek, near Hamilton, 

 Western Victoria. — Balcombian. — Eocene. 



Observations. — This is apparently the forerunner of our living 

 Astele subcarinata, Swainson, but it may be very readily separ 

 rated, and it may also be noted that it is the squat adult form 

 which appears to develop the greatest affinity. 



Eutrochus fontinalis, sp. nov. (PL XIX., Fig. 9). 



Description. — This, though a smaller shell, is closely related 

 in many of its characters to the foregoing species, but differs in 

 its more slender form, its fewer and less regular spiral threads, 

 slightly coarser ornament, narrower and more circular base bear- 

 ing broader flattened spiral bands with obscure beading, com- 

 paratively narrow and shallow umbilicus margined by at least 

 three distinct beaded spirals, and robust columella. 



Dimensions.- — ^Height, 15 mm. ; diameter of base, 13 mm. , 

 height of aperture, 4 mm. ; breadth of aperture, 5 mm. : dia- 

 meter of umbilicus barely 2 mm. Smaller specimens down to 

 height 6 mm., diameter of base 5 mm. 



