MOORE—AUSTRALIAN MESOZOIC GEOLOGY. 255 
depressed ; the umbones are more mesial, less recurved and less pro- 
minent; the area is larger, its proportions being as 1 to 14 com- 
pared with the costated portion of the shell; in 7’. costata it is as 
1 to 23; 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 lamelle; anterior to the carina is a well- 
marked smooth, depressed, oblique sulcus; the cost are numerous, 
short, simply and concentrically curved, rising upwards to meet the 
anterior border at a considerable angle ; in 7’. costata the cost meet 
the border horizontally with a shght undulation; in the advanced 
stage of growth the costee are continued postically across the carina 
and area, forming a slight undulation as they cross the depressed pos- 
tero-costal furrow. These several characters will in the aggregate 
serve sufficiently to distinguish it from all the known European 
forms of the costated Trigome.—J. L.] 
59. TRIGONIA LINEATA, sp.n. Pl. 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 carine absent ; shell gradually sloping to the front ; surface 
with close-set regular transverse concentric strie, 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 there- 
fore 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 7. 
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 Rheetic genus, 
which, moreover, never attains the size of this shell. 
From the Wollumbilla deposit. 
56. TEREDO AUSTRALIS, sp.n. Pl. XII. fig. 11. 
Shell small, convex, rather quadrate ; umbones mesial ; surface 
with a curved furrow proceeding from the umbo to the centre of the 
yentral margin, and with numerous transverse striz, which pass 
obliquely into the mesial furrow, especially from the anterior side ; 
anterior end with six or seven faint, close longitudinal striz, which, 
decussating the transverse lines, give it a wavy look; anterior mar- 
gin 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 Cucullew, Trigone, &e. of Oolitic age, from 
Western Australia, 
