HORN nXPEDITION—MOLLUSCA. 
199 
Localities. —McDonnell Range for type, Waterhouse ; Ifart R.ange, J. East; 
Burt Plain, Horn Exped.; Everard Range, in S.A., Cavanagh Range and 
between Fraser Range and Yilgarn in W.A., Elder Exped. ; Lake Eyre basin, at 
most localities as bleached shells ; Mann’s Creek, twenty-eight miles north of 
Peake, J. Chandler ! ; IMount IMargaret, J. East!; Kewson Hill, Dr. Cleland ; 
Mount Nor-west ! ; Teetulpa, J Macleod ! ; Wilson and Carrieton in Flinder’s 
Range, Bednall. 
Thersites (Badistes) fodinalis, Tate. 
Reference— Hadra fodinalis., Tate, Ti’ans. Roy. Soc. S. Aust., vol. xvd., 
p. 63, pi. i., ligs. Lr-lr, 1892. 
Localities. —Waukaringa, between Petersburg and the boundary of New South 
Wales, for type, extending thence to the Broken Hill district ! Between Victoria 
Spring and Fraser Range, one ex.. Elder Exped. 
Central Australia:—This is by far the most widely-spread and abundant snail 
over the region explored by the Horn Expedition. Its most southern station is 
on the Cretaceous outliers about Sullivan’s Creek ; dead shells, however, had been 
observed much further south, either strewn over the surface or in river-rejecta¬ 
menta, as about Crown Point, at the Goyder, and Lilia Creek ; on the bare lime¬ 
stone surfaces between Waterhouse Range and the sources of Alice Creek, and 
thence to the River Hugh, dead-shells are very abundant, and, in the aUsence of 
shelter, it may be inferred that the species is there extinct. Generally this species 
may be found secreting under rocky ledges in the James and George Gill Ranges 
on the south and McDonnell and Hart Ranges and Burt Plain on the north, but 
it also burrows in marshy places, as at Illamurta. 
Variation. —The colour of the epidermis varies from a mahogany-brown to 
pale straw; sometimes unicolorous, but usually the basal half or third is paler. 
The size of the shell varies within the following extremes:—24 by 21 ••'5 == 
100 : 90 and 14 by 12 = 100 : 89. A common size of the smaller sorts agrees 
with that of the type, which is 17 by LP.o = 100 : 85. The large form prevails 
in the moister habitats, though both occasionally occur together. The shape 
varies from sul)globose to almost planulate, the extremes being indicated by the 
following proportions of width to height :—100 : 90 and 100 : 66’C. The following 
table of measures exhibit a gradation between the extremes :— 
