S.A. NAT., VOT.. XlV. 
May, 1933 . I^y Bernard C. Cofion and F. K. God f try. 
95 
SPIRATELLIDAE. 
\ cry delicate. siibulolMjse, spiral, sinistra!, small, translucent, 
with slieln tellowish colourinir when tenanted; operculum spiral, 
very delicate, glassy, transparent. Animal twisted like the shell 
and wholly retractile, with a tlorsal ]’>a!!ial cavity, and a ventral 
columellar muscle; a long extensile aypendage on the right side 
of tlie niantlc margin and somewhat ventrally; posterior lobe of 
foot, which bears the operculum, is hollotved out on the middle 
of its free margin; fins toward their distal extremity beset with 
muscular fibres. 
Spiratella Blainvilic 1817. Umbilicate, with left-handed 
spiral turns gradtially increasing; smooth or striated; mouth 
rather large; columella not prolonged into a rostrum; operculum 
semilunar, with a right-handed spiral of few whorls, lype— 
Clio helicina Phipps. Animal with an indistinctly defined head, 
which is only marked externally by the lips on the border of 
the mouth and by the tentacles; fins elongated, enlarged, trun- 
cated. 
S. inflata d'Orbigny 1836 {Atlanta) (— Spirialis rostralis 
Ihdoux & Souleyet 1840). PI. fig- 20. Subdiscoldal, very 
thin, trans|-arent, smooth, umbilicate; spire sinistral, depressed, 
not raised above the last whorl; whorls three, convex; mouth 
heart-shaped; peristome acutCj produced anteriorly to a long 
slightly curved beak; operculum ovate, glassy, paucispiral. Creat- 
est diam. 1.5 mm. Dredged — Neptune Islands, Cape Borda, 62- 
104 fatlioms. Also Western Australia — 80 miles west of F.ucla, 
80 fathoms. Distribution — All warm seas. (Atlantic, 42°\. to 
40'S). 
S. bulimoides d'Orbigny 1836 {Atlanta). Oblong, very 
thin, transparent, snuioth; spire elongated, sinistral, apex sub- 
acute; whorls six, convex; mouth ovate, angulated anteriorly; 
columella somewhat arcuate; outer lip thin, sharp; inner llg 
and sutures often pinkish; operculum ovate, glassy, paucispiral. 
ilcight 2, diam. 1 mm. Recorded from South Australia (Verco 
Af.S.) In all warm seas, but not so common as S, injiata d’Or- 
bigny. 
TETHYIDAE ( == Aplysihhir). 
“Sea Hares." Shell thin, horny, nearly or entirely 
covered by the mantle shield-shaped, in the form of a 
c(;ncave plate, sometimes absent. Distribution — almost world 
wide, tropical and temperate, in shallow coastal water. 
Fossil — Tcirtiary (doubtful). Animal slug-like, not pro- 
tected by a shell, semioval when at rest, but capable of consider- 
able extension, of a fleshy substance, neck and head narrower than 
