36 
J. R. RICHARDSON 
Occurrence. Australia; Upper Oligocene, Miocene, 
Recent. 
Diagnosis . Sulcate. Beak erect to nearly straight; 
beak ridges sharp; symphytium wide; hinge line 
slightly to strongly curved. Hinge platform with 
shallow hinge trough, variable in size; cardinal 
process with swollen anterior process. Loop with 
ascending and descending branches fused an¬ 
teriorly. 
Comments. The diagnosis of the genus given by 
Richardson (1987) has been slightly modified 
following study of the two Tertiary species. The 
beak of the Recent species Magadinella mineuri 
is one-fifth to one-sixth the shell length, the 
symphytium is slightly concave without a 
median ridge, the cardinal margin is strongly 
curved, and the cardinalia occupy approxi¬ 
mately one-third to one-quarter the length of the 
dorsal valve. In size and convexity M. mineuri 
and M. woodsiana are similar, but the cardinal 
margin of M. woodsiana may be slightly to 
strongly curved, a median ridge is variably de¬ 
veloped on the symphytium, and the hinge plat¬ 
form is shorter relative to dorsal valve length. M. 
hamiltonensis is smaller, not heavily thickened, 
and the beak, hinge platform, and septum are all 
shorter than in the other two species. 
Magadinella woodsiana (Tate, 1880) 
Fig. 3A-F 
Magasella Woodsiana Tate 1880: 163-164, pi. 10, 
fig. 3a-d.—Tate 1899: 256-257. 
Magasella compta .—Pritchard 1896: 142-143 [par- 
tim., non Anakinetica compta (Sowcrby in Strezlecki, 
1945)]. 
Magadinella woodsiana .—Thomson 1915: 400- 
402, fig. 13a-c.—Thomson 1927: 277-278, fig. 92a- 
c. 
Type material. Syntypes SAM T886A-K, M, N, from 
Morrundi, River Murray, South Australia. Horizon 
unknown. 
Other horizons and localities. South Australia. Mount 
Gambier Limestone (Janjukian, Upper Oligocene): 
Mount Gambier. Victoria. Caldcr River Limestone 
(Janjukian, Upper Oligocene): Wilks’ Localities 3 and 
4, Aire coast. Point Addis Limestone (Janjukian, Up¬ 
per Oligocene): Point Addis; Aircys Inlet: Kawarren. 
Sandford Limestone (Janjukian, Upper Oligocene): 
quarry on south side of Runymede Road, Sandford 
All material cited is housed in the Museum of Vic¬ 
toria. 
Measurements. (In mm; specimens from the Point 
Addis Limestone.) 
Specimen 
Total 
length 
Dorsal 
valve 
length 
Breadth Depth 
NMV P17341 
21.8 
18.6 
17.2 
11.2 
NMV PI34223 
18.0 
14.0 
12.1 
9.9 
NMV PI34224 
18.4 
15.0 
12.4 
10.8 
NMV PI34225 
17.1 
14.7 
11.2 
111 
NMV PI34226 
19.2 
15.6 
10.9 
10.0 
NMV PI34227 
17.4 
13.9 
11.5 
9.8 
Description. Outline variable, pyriform to ovate 
(narrowly to broadly) with maximum breadth at 
mid-length or farther forward; moderately to 
strongly biconvex. Beak nearly straight to sub¬ 
erect, one-quarter to one-eighth ventral valve 
length; symphytium flat to slightly concave, 
median longitudinal ridge variably developed: 
cardinal margin slightly to strongly cuwed. 
Hinge platform with hinge trough between 
medial borders of fused crural bases and socket 
ridges; cardinal process anterior surface variable 
in size, confined to posterior area or extending 
to posterior border of platform, not fused dor- 
sally. Septum low, blade-like anteriorly, crest 
rounded posteriorly. Loop with ascending and 
descending branches fused anteriorly, separate 
posteriorly. 
Comments. M. woodsiana is found in greatest 
abundance in the Point Addis Limestone. The 
preceding description is based on examination 
of hundreds of specimens from a single horizon 
and supplements Tate’s description of the 
species from Morrundi, an area from which ad¬ 
ditional material is probably not obtainable. 
Magadinella hamiltonensis sp. nov. 
Fig 3G-L 
Name. From the type locality. 
Type material. Holotvpe NMV PI34228 and para- 
types NMV P134229-P134233, PI34241, PI34242. 
from the Muddy Creek Marl (Balcombian, Middle 
Miocene), Muddy Creek, Hamilton, Victoria. 
Tig. 3. A-F, Magadinella woodsiana (Tate, 1880). A, NMV PI34210, dorsal interior, x 3.5. B-D, F.NMV 
PI 7341, dorsal, lateral, anterior (ventral valve uppermost) and ventral views, x 2.5. E, NMV P134211, ventral 
interior, x 2.25. G-L, Magadinella hamiltonensis sp. nov. G, paratype NMV P134229, dorsal interior, x 5.5.H.l. 
K, L, holotype NMV PI34228, dorsal, ventral, lateral and anterior (ventral valve uppermost) views, x3.4. J. 
paratype PI34230, ventral interior, x 3.4. 
