MOORE AUSTRALIAN MESOZOIC GEOLOGY. 255
depressed ; the umbones are more mesial, less recurved and less prominent ; the area is larger, its proportions being as 1 to 1-1/2 compared
with the costated portion of the shell ; in T. costata it is as
1 to 2-1/2 ; the area is not concave, but has a median groove replacing
the usual median carina, and there is scarcely any inner carina ; the
marginal carina is very large and broad, but not much elevated, with
regular large transverse lamellae ; anterior to the carina is a well-
marked smooth, depressed, oblique sulcus ; the costae are numerous,
short, simply and concentrically curved, rising upwards to meet the
anterior border at a considerable angle ; in T. costata the costae meet
the border horizontally with a slight undulation ; in the advanced
stage of growth the costae are continued postically across the carina
and area, forming a slight undulation as they cross the depressed postero-costal furrow. These several characters will in the aggregate
serve sufficiently to distinguish it from all the known European
forms of the costated Trigonioe. — J. L.]
55. Trigonia lineata, sp. n. P1. XIII. fig. 12. Myophoria, M'Coy.
Shell thick, equivalve, inequilateral, gibbous, as broad as long ; umbones convex, recurved towards the anterior margin ; anterior side and ventral margin rounded ; posterior angle somewhat rounded ; marginal carinas absent ; shell gradually sloping to the front ; surface with close -set regular transverse concentric striae, about twenty in number, which on the anterior margin possess depressed tubercles.
Two specimens of this shell have been sent over — the one a cast showing the teeth, the other with the test much abraded and therefore exhibiting probably but imperfectly the surface characters that might be present on better examples.
The contour and the ornamentation of this shell remind us of T. gibbosa of the Portland Oolite, but it is more generally rounded and gibbous than that species.
Professor M'Coy, in his catalogue of the Australian Mesozoic species, places it under Myophoria ; but it does not possess the oblique keel and the acute posterior side of that Permian and Rhaetic genus, which, moreover, never attains the size of this shell.
From the Wollumbilla deposit.
56. Teredo australis, sp. n. P1. XII. fig. 11.
Shell small, convex, rather quadrate ; umbones mesial ; surface with a curved furrow proceeding from the umbo to the centre of the ventral margin, and with numerous transverse striae, which pass obliquely into the mesial furrow, especially from the anterior side ; anterior end with six or seven faint, close longitudinal striae, which, decussating the transverse lines, give it a wavy look; anterior margin reflected and gaping.
A numerous colony of these shells was attached to a piece of fossil wood, the impression only of which is left in the stone. They occur in the block with Cuculloeoe, Trigonioe, &c. of Oolitic age, from Western Australia,
