256 
Muddy Creek, Gelibrand River, Maude, Mitchell River, Camper- 
down, Moorabool Valley, Portland (Woods), Porr Farry 
(Strezleckz) (Victoria). 
Post-Eocene.—Beaumaris and Spring Creek (Victoria). 
M. deformis, 7'ate, 1, p. 165. 
Eocene. — ALDINGA Bay, Muloowurtie, Kangaroo Island 
(South Australia). 
M. lunata, spec. nov. PI. viii., figs. 3-3a. 
EocENE.—CROYDON-BORE, near Adelaide, atfrom 400 to 1,230 
feet ; River Murray Cliffs at Mannum ; Mulgurdawa-bore, near 
Wellington, at 213 ft. (South Australia). Belmont near Geelong 
Vict. 
\ Shell small, surface smooth or with a few distant depressed 
growth-folds, largely and copiously punctated (visible under a 
pocket lense) about 250 pores in a field of 1:1 mills. diameter; 
suborbicular to subpentagonally oval in marginal outline, plano- 
convex in sectional outline ; hinge-line arched, not so long as the 
greatest width of the shell. 
Pedunculated valve. medially elevated, its front margin 
indented by a deep, narrow, concave sweep corresponding with the 
medial elevation. The beak is of moderate size, hardly up-curved, 
its truncated foramen being nearly flush with the umbonal area 
of the brachial valve ; foramen of moderate size. 
Brachial valve flat except towards the front, where it is 
abruptly depressed in the middle line. 
The internal characters are the same as in UW. deformis, the 
septum reaches nearly tc the opposite valve. 
Dimensions of an average - sized specimen. — Length, 5:3 ; 
height, 6 ; sectional diameter, 2°5 mills. 
The species is related to MW. deformis, but differs by more 
orbicular outline, stout and short beak, larger foramen and flat 
brachial valve. It simulates TZerebratella Woodsii, but its 
anterior depression is shallower and more abrupt. The numerous 
examples, all of a nearly uniform size, from the Croydon-bore 
should dispel the doubt that they are young torms of 
M. Woodsiana, which does not occur there. 
M. Tenisoni, Woods, 1865; id., Tate, 1, p. 165. 
Kocene.—Movunt Gampier (8. Aust.) and Portland ( Vict.) 
| Woods]. 
' M. Woodsiana, Jaze, 1, p. 163. 
KocENE.—River Murray Cuirrs, Mount Gambier, Aldinga 
Bay (S. Australia) ; Muddy Creek, Gelibrand River, Mornington, 
Birregurra, Moorabool Valley, Camperdown, Airey’s Inlet 
(Victoria). : 
