41 
flattened or slioulder-liko around the sutures ; l)ody -wliorl large, inflated, 
rapidly increasing in size. Sutures cliaunclecl. Mouth ovate, straight above, 
narrowed below ; outer lip very convex in outline; inner lip straight, a little 
thickened, hut not much retlected. Umbilicus variable, usually slit-like. 
Surface transversely striate on the body whorl, becoming rugose with age; 
sculpture of the older whorls unknown. 
Ohs. — It is only since I examined a number of opalised shells from 
White Cliffs that I have acquired wdiat I believe to he a true conception of 
Moore’s yatica variahilis. INIoore described three allied forms of Gasteropods 
from the Queensland Cretaceous, viz., (a) Natica variahilis, {h) N. oriia/is- 
slma, and (a) Delphinula rejlecta. The second of these {h) may he dismissed 
from present consideration, as it does not seem to he ])resent in the collection, 
hut of the other two Moore said : — 
{a) “ S})ire of 3-4 volutions, somewhat depressed ; body whorl increasing 
rapidly in size and extended, aperture ovate, umbilicus small. 
[c) “ IVhorls 3-4, spire slightly elevated, volulions separated hjj an 
encircling sinus, body Avhorl much increased, aperture circular, with a thick 
rejlected Up.'" 
The italics are mine, and tlie characters so accentuated are the only 
distinctive features not common to tlic two. 
It may he explained in passing that it has been customary with us to 
refer all our Cretaceous Naticiform shells with a much inflated and expended 
body whorl and encircling sinus to N. variahilis, Moore, on the grounds that, 
from the poor state of 2 )reservation in which these shells have always been 
presented to us, the actual mouth was never seen, nor the sculpture preserved. 
Erom these causes it is quite probable that I, in common with others, have 
in the past confused these species one Avitli the other . Erom M^hite Cliffs 
we now liaAm two shells generally alike, l)ut Avith sufficient of the mouths 
preserved to shoAV that one (c) ])ossessed an ovate mouth, small slit-like 
umbilicus, and a scarcely at all reflected inner lip ; and another (c) Avith an 
ovate mouth, sometimes a similar umbilicus, and a tliick greatly reflected 
inner lip. When these cluiract<'rs arc not vusibh', and in the absence of any 
differentiating sculpture, it is impossible, I believe, to separate the species. 
Iloth possess a spire variable in height, a clianneh'd sutma' and an increasing 
i' 
