Souf k . / ust ral la h Slirlls 
42 . 
S.A., NAT., VOL. XIV 
NOvkmhkk. 1932 . 
mouth ,or a Rissoinid with a Strombiformid protoconcli. I'hr 
higher value of the nuclear character in cjassification requires 
it to be placed in Strombiformidae, TypcStUifer tasmanicui 
Tcnison- Woods 1876 (Stylifer) . 
P. tasmanica Tenison-Woods 1876 (Stylif^r), “The I’as- 
manian Pscudorissoina.” Small, pyramidal pellucid, shining; 
milky white; smoth’; protoconch mamillatfc^d, sinisti^al; adult 
whorls six, convex; suture impressed, scarcely sloping; mouth 
obliquely pyriform; outer lip produced, incurved, emarginatc at 
each side; inner lip inconspicuous but rcflexcd. Height 4, diam.. 
1.5 mm. Rare, (“rype locality — Blackman’s Bay, Tasmania). 
STILIFERIDAE. 
“Sca-urc!iin Snails.” Description of shell is that of the 
only known genus Stiiijer. Distribution— Europe, West Indies, 
Australasia, Polynesia, Philippines. Fossil — Records doubtful. 
Animal covered with cilia; mantle spread over the base of 
the shell; liead snoul-likc with side lobes, terminating in a suc- 
torial mouth which is unarmed; tentacles slender, tapering; eyes 
sessile, placed on the neck behind the tentacles; foot tongue- 
shaped, partly tubular, with a slit in the sole, produced anteriorly, 
rudimentary behind. Sexes seperate. 
Urchin-snails are found among the spines of Sea-urchins; 
also burrowing or Imbedded in the skins of Star-fishes, and pro- 
ducing tumors, often of considerable size. They have been de- 
tected enclosed in the basal portions of the spines of a Cidaris 
(Sca-urchin), which had been enlarged for its accomodation. 
The suctorial mouth strengthens the supposition that food con- 
sists of extremely soft or semi-fluid matter, and not of any organ- 
isms which have any degree of solidity. Many believe that 
Urchin-snails subsist on the excretions of Echinoderms; this op- 
inion is founded on the fact that specimens invariably occupy 
only the area of the anal orifice. Some which have been watched 
with close and almost unremitting aueiition for many hours, al- 
though they were most lively, nestling or slowly crawling about 
among the spines of an Echinus, never attempted to touch with 
the mouth either the protruded suckers or the pedicellariae of the 
Echinus, or any part of it$ investing membrane. Urchin-snails 
do not appear to put their host to the slightest inconvenience. 
None has been noticed in any other habitat. They are not 
parasites, and their scavenger habits are said to be not unlike 
those of dung-beetles. 'I’hc spawn is deposited on the upper sur- 
face of the Echinus on which they settle. As many as forty 
dusters of spawn, with at least a hundred fry in a cluster, have 
been observed on the upper part of a single sea-egg; this is a 
