South JustraUau Shulls. 
s..\* XAT., VOL. 
MARCH 27'm. 
XV. 
1934. 
wrinkles, next as radial riblets; where wrinkles commence the slit 
begins; dorsum in front is a uniform convex curve, behind it a 
continuous concave curve; perforation occupies the middle third 
of dorsal slope, and is lanceolate; between it and the protoconch 
its previous site is closed by a sunken lamina with subdistant 
erect transverse lamellae, convex posteriorly; between it and the 
anterior margin is a differentiated rib, broader and higher than 
7 he rest, fissured superficial!v throughout; in its upper part the 
fissure is as wide as the perforation, but nearly closed internally 
by horizontal laminae from the sides; it gradually contracts an¬ 
teriorly to a fine line; in its upper half the fissure communicates 
with the interior, in the lower it is shut off; slit fasciole and 
perforation are bounded on. each side bv a delicate erect lamina, 
highest at perforation, in front of which the laminae gradually 
approximate to form the differentiated rib; from protoconch to 
margin this lies a little to right of actual median line of shell; 
radial ribs, well rounded, nearlv smooth, about as wide as their 
interspaces ,sixteen primary, increasing bv intercalation of secon¬ 
dary and tertiarv riblets to ninety in a shell of ten millimetres 
length, and cumulating the margin; posterior ribs broader, closer; 
mternalK a small shelf or septum convex towards the interior, 
with a sharp simple margin anteriorly hides the upper fourth of 
the perforation, being attached to shell at a distance from mar¬ 
gins iff perforation about ecpial to width of perforation, it gets 
gradually narrower and less obvious posteriorly; its dorsal sur¬ 
face slopes up to the slit fasciole; from perforation anteriorly 
runs a gutter to the margin; in older examples this becomes a 
thin central ridge; with age the shell grows more rapidly poster¬ 
iorly. so that apex gets less eccentric, and the back part becomes 
very fiat and sloping. Length 18, breadth 15.4, height 4.7 mm. 
apex 5.4 mm. Irom posterior end. ( 1 ype locality—150 fathoms, 
off Cape Jaffa. South Australia). Also 300 fathoms. Cape Jaffa. 
Different individuals display the varied aspects at successive 
stages, first a depressed spiral shell with a simple aperture; then 
aii cmarginula-like form, with a slit and slit fasciole; then a 
rimula-1 ike shell, with a perforation just above the margin, con¬ 
tinued as a narrow fissure to the border, and finally with tne 
fissure closed and the perforation complete. 
P. fumarium Hcdlev 1911 (Puncturclla). PI. L fig. 14. 
Shell laterally compressed, thin, translucent, erect, posterior pro¬ 
file usually slightly .convex and anterior slightly concave; delicate 
concentric growth lines, small tubercles, conspicuous in profile, 
are set in radial rows; summit irregularly notched, subcircular 
seen from above, cleft with a short, steep posterior limb seen 
