FOSSILS OF NEW SOUTH WALES. 689 
near the anterior side of, or across, the posterior muscular impression. The valves are 
very thin at middle, being hardly 3, of an inch in the first of the following species, and 
are thickened below towards the margin, a short distance from which the same species 
is half a line thick. The palleal impression stops abruptly just before reaching the pos- 
terior muscular impression. Our specimens show well the exterior and interior of dif- 
ferent species; but the teeth of the hinge have not been made out. The exterior surface 
is unevenly marked with concentric striz of growth, and is convex quite to the anterior 
margin, 
22. ASTARTILA INTREPIDA (Dana).—Thick, length but little greater than height, 
anterior part about + whole length. Lateral surface evenly convex, marked quite neatly 
with concentric striz, Anterior muscular impressions excavate ; the smaller subquadrate, 
the larger transverse, with a number of fine vertical lines on the posterior quarter.— 
Length 13 inches; height ;8°, L.; thickness $2, L.; apical angle about 120°.—Plate 3, 
fig. 5, 5 a, different views, natural size ; 6, larger anterior muscular impression enlarged ; 
c, smaller anterior muscular impression enlarged. 
District of Illawarra at Wollongong Point. 
This is a thick species distinguished by its anterior muscular impressions and general 
proportions. The cast from the beak obliquely downward is strongly flattened; and 
between this area and the large anterior muscular impression, the surface is somewhat 
convex, and moreoyer it is smooth without minute corrugations, The stric of the ex- 
terior surface are strong and quite neat although somewhat irregular, and the surface is 
a little shining. 
Astartila intrepida, Exped. Foss., Amer. Jour. Sci., ii. Ser., iv. 155. 
Pachydomus ovalis, [¢] M’Coy, Ann. Mag. Nat. Hist., xx. 302, pl. 14, fig. 4. 
23. AsTARTILA cypRINA (Dana).—Oblong, thick, length one-third greater than 
height. Exterior surface coarsely and unevenly concentric striate. Inner surface of 
valves minutely rugulose, and below the palleal impression vertically subplicate. Mus- 
cular impressions excavate ; the smaller anterior oblong, sigmoid ; the larger subquadrate, 
3D) 
very convex, marked vertically with a few lines, the posterior hardly excavate——Length 
2); inches ; height 54%, L.; thickness ,5,8, L.; apical angle about 118°.—Plate 3, fig. 6, 
6 a, views of cast, natural size; 6, large anterior muscular impression, (from cast,) with 
commencement of palleal impression; ¢c, d, small anterior, from different specimens 35 e, 
J, posterior muscular impressions. 
Wollongong Point, District of Illawarra. 
The vertical plications below the palleal impression are characteristic. It is also pecu- 
liar in the character of its larger anterior muscular impression, and its proportional 
dimensions. Also, the cast from the beak downward is but slightly flattened, and the 
space between the flattened area and the muscular impression is convex, owing to the 
continuation upward of the convexity of the muscular impression itself. 
Astartila cyprina, Exped. Fossils, Amer. Jour. Sci., ii. Ser., iv. 155. 
24. ASTARTILA CyTHEREA (Dana).—Thick, a little longer than high. Beak thrown 
a little forward. Exterior surface very coarsely concentric striate or costate; inner sur- 
face of valves smooth, Smaller anterior muscular impressions scarcely excavate, oblong 
sigmoid ; larger strongly excavate and very abruptly so on the upper side, oblong sub- 
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