44 
Toil lEBDALE. 
margin a litth? dilated above. Greatest diameter 7 mill., smallest 6; height ,1. 
Hab. Dupuch’s Is., West Australia (Kichardsoii). This small but prettily 
sculptured species is chiefly characterised by the flue rihlets, and the micro- 
scopic spiral striations, ivhicli are not, as in some other species, interrupted 
by till' rihlets, but are continuous over them. The inferior surface is slightly 
shining, the upi)or not so.” 
Smith, later, added : “This is the largest of the W. Australian Fatulae 
at present described. Several bear a very strong family resemblance, but 
appear to be distinguishable in certain minute details.” 
FAMILY MICROCYSTIDAE. 
This family comprises many small llattened conoid shells of thin shell 
and glassy appearance, whose exact relationship must be determined by 
anatomical examination. So far only one group, with two species, has been 
discovered and in shell characters it has shown peculiarities sufficient to 
differentiate it from all East Australian groups. 
Genus WESTRACYSTIS Iredale 1933. 
1933 — We.-itrari/stis Iredale, Rec. Austr. Mus., Tol. XIX, p. 56, Aug. 2. 
Orthotype Lamprocijstis JiRsn Smith. 
Smith described the tyi)e s]iecies in the genus Lamprocystifi, observing 
that it was “well characterised by the peculiar dentiform thickening of the 
columella and the ridge which ai'ises from it, and passes u]} the very con- 
tracted umbilicus.” Hedley transferred it to Mierocystis, biff it was obviously 
more closely related to Lamprocystif!. 
Westracystis lissus Smith 1894. 
1894 — Lamprocystis liufta Smith, Froc. Malac. Soc. (Loud.), Vol. T., ii. 86, 
]il. VIL, tigs. 22-23, .Iiine; (^tueen’s Islet, Fairy Island tWalkcr); 
Burner (error for BaiTier) Ranges (Cox), North-West Australia. 
The first locality, (^uemi’s Islet, is here selected as the type localit.v 
Smith’s di'sci'iption reading; “Shell narrowly i)erforate, orbicular, depressedly 
conoid above, thin, horn.v, shining, seul])lured with very thin growth striae 
and microscopic spiral strialions; whorls live, lillli* conve.x, narrowly inargi- 
nate below the suture, Ihe last whorl slightly descending; spire shortly coll- 
oidal, rather obtuse at the apex; aiierture obliquely lunate, small; peristome 
thin, the margins apiiroaching, .joined by a thin callus, tiie coiuiiu'lla thick- 
ened, forming a jiceuliar tooth aliove the perforation; umbilicus very narrow, 
furnished with an intrusive keel terniinating at the colunudlar tooth. Breadth 
8.5 ; height 5 nim.” 
Westracystis tentus sp. nov. 
Flate III., fig. 14. 
A large number of si>eciiuens, lollecled by W. W. Froguatt in the Bar- 
rier Range, all show an engraved umbilicus, a feature not recorded bv the 
veiw accurate Smith in his descripition of IF. Unna, though he carefully ex- 
amined the umbilical features. Yet this is a feature of many inembiu’s of this 
family. 
The Barrier Range species is smaller, loss elevated, the umbilical ridge 
less notable and the umbilical cavity is filled with a gum-like matter. It 
measures 7 by 4.25 mm. against 8.5 by 5 mm. The umbilicus is also quite open, 
and though narrow would not be termed “very contracted.” 
