Tertiary. | PALZONTOLOGY OF VICTORIA. [ Mollusca. 
is abruptly marked by the ridges being only radiating. The trans- 
verse ridging, though common in the Mesozoic Trigoniz, is not 
found in the recent species. 
Very abundant in the sandy beds of Bird-Rock Bluff (A* 22 and 
A‘ 24), 
EXPLANATION OF FicurEs. 
Plate XIX.—Fig. 4, average sized specimen of left valve, natural size. Fig. 4a, profile of 
ditto. Fig. 5, smaller specimen of right valve, natural size. 
Puate XIX., Fias. 5, 6, 7. 
LIMOPSIS AURITA (Broccut sp.) 
y° 
[Genus LIMOPSIS (Sassr). (Sub-kingd. Mollusca. Class Dithyra. Order Pectinacea. 
Fam. Arcide.) 
Gen. Char.—Shell suborbicular, slightly oblique, moderately convex, margins closed. Hinge 
in each valve composed of 2 equal curved rows of transverse small numerous teeth ; beaks 
small, separated by a flat, triangular, ligamental area, with a triangular cartilage pit in the 
middle under the beak. ]} 
Description.—Obliquely ovate when old, more orbicular when young; beaks 
small, moderately tumid, rounded, slightly projecting beyond the hinge-line; valves 
moderately convex, most so at about the middle of the length ; cartilage pit large, 
an equilateral triangle with 4 or 5 teeth much smaller than the lateral ones under it 
in large specimens, but few or no teeth under it in small specimens, 5 (or some- 
times 6) larger ones on each side of the cartilage pit; ligamental area flattened, 
slightly concave, faintly striated transversely, increasing in width with age, and 
forming obtuse-angled, undefined, very short ears on each side; anterior muscular 
impression, with a prominent posterior edge; inner margin of the valves with a broad, 
flat, smooth, bevel-like space round the thin sharp edge. External surface with 
numerous close irregular imbricating concentric laminar ridges (4 or 6 in one line at 
3 lines from the beak). Well-preserved specimens show under the lens close, obtuse, 
radiating strie, about twice their thickness apart on the flat portion of tle concentric 
lamin, each seeming to widen and dichotomise towards the edge, which it does not 
pass (about 10 in one line at 8 lines from the beak). Ordinary length from beak, in 
the direction of the obliquity, to opposite margin, 7 lines (one specimen 10 lines 
lone); proportional greatest width at right angles to length, =39,; length of hinge- 
line, 3°, ; depth of the two valves together, 34°, Smaller specimens are flatter, and 
larger ones are proportionately deeper. 
. Be eENes Arce aurita (Brocchi), Conchiologia Fossile Subapenninz, t. xi., 
To the naked eye most specimens seem to be only concentrically 
marked, and in some even the lens fails to show the interrupted 
longitudinal strie, except on the sides ; they are generally, how- 
ever, more distinct in the Australian specimens than in those from 
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