MOORE AUSTRALIAN MESOZOIC GEOLOGY. 249
crossed by regular concentric fimbriated striae, which in the interspaces
are produced beyond the shell. The umbo and auricles are
wanting, and the shell is otherwise imperfect.
Loc. Wollumbilla.
26. Perna gigantea, sp. n.
Shell very large, measuring 6-1/2 inches broad by 5-1/2 inches in length, inequilateral, flattened ; umbones depressed and rather produced ; anterior byssal area rounded, hinge-line rather oblique, extending one-third the width of the shell; posterior end oblique, rounded and folding towards the ventral margin, which with the anterior end is rounded.
It is in a sandy boulder somewhat resembling green sand, which under the lens is seen to contain black-looking chloritic grains. The boulder contains Lingula ovalis and Mytilus, which show the Perna to be of the same age as the Wollumbilla series.
It is the only example known, and is from Wollumbilla.
27. Arca plicata, sp. n. Pl. XII. fig. 6.
Shell small, quadrate, left valve convex ; hinge-area wing-like and extended, angular ; posterior margin truncated ; surface with a few wide radiating striae, several of the more distinct of which are on the angulated portion of the posterior end.
Only one example is known. It is from Wollumbilla, and the block also contains many Lingular and small Pectens.
28. Arca prelonga, sp. n. Pl. XIV. fig. 7.
Shell transverse, inequilateral; umbones rather close, anterior; hinge-line long, with numerous close-set teeth ; posterior side extended and slightly angulated, with a depressed keel crossing from the umbo to the posterior ventral margin. The specimen does not exhibit the finer ornamentation of the test.
It is from Wollumbilla.
29. ASTARTE APICALIS, Sp. n. Pl. XIII. fig. 11.
Shell small, trigonal, flattened ; umbones very acute, almost mesial ; anterior and posterior margins oblique ; ventral margin straight ; surface ornamented with distant raised and straight transverse lines of growth.
Several specimens of this species are attached to one of the blocks from Western Australia. It is associated with Trigonia Moorei, Lyc, Cuculloea, &c, and is evidently to be referred to the Inferior Oolite.
Loc. The Greenough district.
30. Astarte Cliftoni, sp. n. Pl. XIII. fig. 10.
Shell thick, ovately trigonal, flattened, inequilateral ; umbones acute, small, anterior ; anterior side short; posterior end the longest, very oblique, and produced towards the ventral margin, which is
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