192 CCELOCION. 



line of plicate-mouthed ancestors stretching back into Meso- 

 zoic time. The senile feature of an uncoiling last whorl 

 Beems to point to C&locion as the last of its ancient race. 



3. P. AUSTRALIS (Forbes). PI. 29, figs. 18, 19; pi. 30, figs. 

 25-29. 



Shell umbilicate, cylindric, slowly tapering to the rather 

 broadly truncate summit; white under a thin greenish-yellow 

 cuticle, which is almost entirely lost in adult individuals; 

 moderately solid. Surface but slightly shining or lusterless, 

 sculptured with thread-like longitudinal riblets, much nar- 

 rower than their intervals. Whorls numerous, somewhat 

 convex, the last noticeably angular at the periphery, pinched 

 into a cord-like keel around the narrow, somewhat funnel- 

 shaped umbilicus; the last whorl becoming shortly free from 

 the preceding in front. Aperture subvertical, pear-shaped, 

 distinctly narrowed above, subangular below, where it is chan- 

 nelled within. Peristome free, a little expanded, the parietal 

 margin with a prominence in the middle, marking the end 

 of a low ridge or lamella running inward. Axis rather large 

 and tubular, encircled by a small spiral cord near the base. 

 In the penult, whorl this cord widens into a flat lamella, and 

 is accompanied by another similar lamella above it on the 

 pillar ; both decreasing and extending downward into the first 

 half of the last whorl. There is also a plica on the outer wall 

 near the lower partition in the penult, and first half of the 

 last whorl (pi. 30, figs. 28, 29, pal.), and a lamella on the 

 parietal wall, beginning within the back of the last whorl, 

 and penetrating about one whorl inward. 



Length 22, diam. above aperture 4.5 mm.; whorls 

 N. Pine River. 



Length 20, diam. above aperture 4.3 mm.; whorls 

 N. Pine River. 



Length 18, diam. 4, aperture 4 mm. long; whorls 11. 

 Forbes ' type. 



Length 18, diam. above aperture 4 mm. ; whorls 9. Warroo. 



Length 18.5, diam. above aperture 4 mm. ; whorls 11. 

 Warroo. 



