Eocene cranioid brachiopod 
313 
margin similarly endopunctate, some of the 
punctae forming linear depressions perpendicular 
to shell edge. 
Dorsal valve 
Dorsal valve (WAM 94.28) subcircular (Figure 
2J-L). Exterior surface has a number of growth 
lines with radiating spines (3 per mm). Valve 
slightly conical in shape, top of cone 0.25 to 0.3 
distance from posterior margin. Interior has 
pronounced limbus slightly angled to interior 
curvature, beginning at posterior-lateral margin; 
extends around the shell. Towards anterior of shell 
it widens, being widest at anterior margin. Shell 
concave, greatest depth at cone top near posterior. 
Posterior muscle scars are slightly raised from the 
wall and parallel to it. Anterior muscle scars on the 
base of shell, triangular in shape. Anterior to these 
scars is a median ridge which extends 0.3 diameter 
of the valve with two large depressions either side. 
Shell endopunctate throughout, endopunctae 
radiating in a linear fashion. 
Intraspecific variation 
The larger the specimen, the greater the number 
of growth lines in the pseudointerarea, each line 
becoming more densely spaced as the shell gets 
larger. Furthermore, the greater the shell size the 
greater the number of radiating lines of spines on 
the exterior surface of the shell. WAM 94.34 has 
interior ridge anterior to the median septum from 
the anterior muscle scars to the margin in an 
anterior lateral direction. The shell is slightly 
convex. Other specimens do not show these 
features. WAM 94.36 and WAM 94.37 are 
markedly depressed anterior to the median septum 
and anterior muscle scars. There is a ridge present, 
dividing area into two equal sized pits. This is not 
observable in WAM 94.29 and WAM 94.34 nor, 
due to wear, is it apparent in WAM 94.30-33. 
WAM 94.35, WAM 94.38 and WAM 94.40,41 have 
a wider ridge or "bridge" between the anterior 
muscle scars and limbus than other specimens 
(Figure 2G). WAM 94.37 shows clearly the 
endopunctae in lines radiating from the 
pseudointerarea margin. These lines change 
direction on the limbus to become perpendicular 
with the shell edge. In WAM 94.38 the 
pseudointerarea is less pronounced than in other 
specimens. Around the endopunctate limbus an 
anterior margin, stemming from the first growth 
line of the pseudointerarea, surrounds the shell. 
This is also present in WAM 94.40 and WAM 94.41. 
The margin is smooth, flat and not punctate. It is 
possible that such a margin was present on the 
other specimens but was worn away. WAM 94.39 
(Figure 2H,I) is appreciably smaller than the other 
specimens. It is flatter internally, lacking distinctive 
muscle scars. The endopunctae produce numerous 
raised areas which appear as tubercles. The middle 
of the three growth lines in the pseudointerarea 
has two flat spines pointing posteriorly. The 
"roughness" of the edges of growth lines in other 
specimens may indicate that they too possessed 
such spines at some stage. 
Tabic 1 Measurements of Westralicrania zenobiae ventral valve dimensions as indicated in figure 1 (all measurements in millimetres). 
Specimen Length 1 
Length 2 
Length 3 
Length 4 
Length 5 
Length 6 
Width 1 
Width 2 
Width 3 
Width 4 
G. Lines 
S.Lines 
WAM 94.29 
8.6 
6.0 
3.3 
1.7 
i.i 
1.4 
7.0 
2.5 
1.2 
1.6 
9 
36 
WAM 94.30 
7.9 
4.9 
3.2 
1.5 
0.9 
- 
7.0 
2.4 
0.9 
_ 
6 
29 
WAM 94.31 
10.3 
6.5 
4.0 
1.9 
1.0 
1.5 
8.6 
3.0 
1.2 
1.8 
_ 
36 
WAM 94.32 
11.7 
- 
- 
- 
- 
2.1 
8.5 
_ 
_ 
2.1 
_ 
28 
WAM 94.33 
7.7 
4.9 
3.5 
1.6 
1.0 
1.9 
6.7 
2.3 
1.0 
2.3 
_ 
27 
WAM 94.34 
9.1 
6.1 
3.9 
1.7 
1.0 
1.5 
7.9 
2.7 
1.2 
1.7 
ii 
35 
WAM 94.35 
7.8 
4.9 
3.6 
1.6 
1.0 
1.0 
6.8 
2.1 
1.0 
1.6 
ii 
28 
WAM 94.36 
9.1 
6.0 
4.5 
1.8 
1.1 
1.5 
8.0 
2.9 
1.2 
1.7 
_ 
26 
WAM 94.37 
9.5 
6.9 
- 
1.7 
1.4 
1.6 
7.4 
2.5 
1.3 
2.1 
_ 
37 
WAM 94.38 
8.7 
5.6 
4.3 
2.1 
0.9 
1.5 
7.7 
2.7 
1.2 
1.9 
_ 
_ 
WAM 94.39 
4.8 
3.3 
2.2 
0.9 
0.6 
1.3 
3.8 
1.0 
0.8 
1.7 
3 
26 
WAM 94.40 
8.5 
6.3 
3.7 
- 
1.1 
2.2 
6.6 
2.5 
1.0 
2.4 
_ 
_ 
WAM 94.41 
9.6 
6.5 
4.0 
1.7 
0.9 
- 
7.3 
2.5 
0.9 
_ 
9 
29 
AVERAGE 
8.7 
5.7 
3.6 
1.7 
1.0 
1.6 
7.2 
2.4 
1.1 
1.9 
N.A 
30 
Nil: G. Lines indicate growth lines and S. Lines indicate ribs on exterior of the shell. 
Dorsal valve measurements: 
SPECIMEN LENGTH WIDTH DEPTH 
WAM 94.28 
WAM 88.373 
7.3 
7.0 
7.8 
7.8 
2.1 
2.1 
