s.A. vr., VOI-. XIV. 
^{\r, 1933 . By Bernard C. Cotton and f. fd. Godfrey. 
AKERATIDAE. 
Oval or cylindrical, thin and fragile, elastic; light yellow- 
brown or green tint; with entirely exposed nearly level spire, deep 
sutural slit, and wide fasciole. Distribution — A lost Seas. Fossil 
—Tertiary. Animal not completely retractile, with long narrow 
head disc, large parapodial lobes reflexed over the shell, and many 
cartilaginous stomach-plates. The young use the parapodial lobes 
as swimming organs. 
Akera Muller 1776 Akeros — hornless. Ovate, or oval- 
cvlindrical, thin, fragile, elastic, with exposed nearl}- level spire of 
several whorls; last whorl acutely keeled at the shoulder, the keel 
bounding a Hat anal fasdolc; mouth nearly as long as the shell, 
rarrmv above and extending in a deep sinus along the suture, 
dilated below and very effuse, permitting all the whorls to be 
seen from the base through the spirally ascending columella;, 
columella very concave, thin, with narrowl}’ rcllexed edge. T’ype — 
:lkera IniUata Muller (British). 
A. soluta Gmelin 1791 (BuHa). Large, fragile, cylindrical, 
tapering towards the ends; periostracum thin, pale yellowlsh- 
hmwn; spiral striatioiis dense; spire slightly projecting, obtuse, 
a terrace of shoulder of whorls, acutely keeled, a ilat, wide anal 
fasciole between keel and the deeply impressed suture; proto- 
conch minute, uptilted. half immersed; whorls nearly five; body 
whorl forming most of the shell; mouth narrow in its uj'^per half, 
with a wide posterior sinus extending back about a third of the 
whorl, lower half dilated ovate, effuse at the base; outer lip fragile, 
arching forward in the middle; columella very concave, with a 
narrowh' refiexed cord-like edge. Height 45, diam. 25 mm. Port 
Lincoln, Ilardwicke Bay, Spencer's Gulf. (Type locality — Zan- 
zibar). Peters records this species from Querimba Is.. Lienard 
from Mauritius, Cuming from the Philippines and Torres Straits, 
Angas from New South Wales. 
A. tasmanica Beddome 1882. “ITc T'asmanlan Akera.' 
Minute, globosel}' oblong, imperforate, thin, glossy; brown, dark- 
er tinted above, with a narrow white band near the shoulder and a 
wider one in the anterior-third; spire truncated, flush with the 
upper margin of the last whorl, separated by a channelled suture, 
terminated by a hyaline bulbous protoconch; last whorl Inflated, 
?.s long as the shell, rounded at the shoulder; mouth contracted 
above, enlarging anteriorly to the arched front; outer lip trun- 
catedly angled posteriorly; columella arched, simple. Height 1.9, 
diam. 1.2 mm. Guichen Bay, Ciulf St. A'incent. (Type locality 
— BrowiTs River Road, Tasmania, 7 fathoms). 
A. bicincta Quo}' &: Gaimard 1833 {BuUa). PL 1, fig. 12. 
‘The Two-banded y\kcra.’’ Ovate-oblong, very thin, fragile; 
white, encircled by two reddish-bands; axial and spiral striations; 
