696 APPENDIX I. 
37. Mmonra axrnta (Dana).—Rather thin; very inequilateral ; oblong, length about 
14 times the height, diminishing much in height posteriorly, rounded anteriorly ; right 
valve a little the highest; flank flattened, but no distinct carina. Palleal impression 
strong, forming a narrow uneven band, abruptly bent below the posterior muscle, not 
reaching quite to larger anterior muscular impression. This last muscular impression 
ovate, subacute above, smooth, with faint horizontal lines. No accessory muscular impres- 
sion on front of beak. Posterior muscular impression quadrate, with upper angle pro- 
longed, smooth, with faint horizontal lines. Apex of beak of cast acutely prolonged. 
Lateral surface of cast, from the beak obliquely downward, a little excavate.—Length of 
cast 23 inches; height 63, L., thickness 36, L., or 2 H.; apical angle of cast 185°. 
—Plate 5, fig. 5 a, b, cast, natural size; c, enlarged view of small anterior muscular im- 
pression. 
District of Illawarra. 
Figure 5 d, is believed to be an imperfect specimen of the shell of the same species. 
The flank is flattened and broad, and the sides are compressed and a little excavate along 
an oblique direction ; surface coarsely concentric striate ; valves moderately thick. Ante- 
rior portion about 2 the whole length. Length 32 inches ; height {65 L.; thickness 775 
L. ; apical angle about 142°.—Wollongong, Illawarra. 
In the notice of the Expedition Fossils, in the Amer. Jour. Sci., i. Ser., iv. 157, this 
specimen is named Cypricardia ? sinuosa. Morris’s second figure of Pachydonwus cart- 
natus, (pl. xi., fig. 4, Strzelecki,) represents a cast, much resembling our figure 34 ; but 
the posterior muscular impression is marked vertically with strong lines. His figure 3 is 
altogether different. Both pertain apparently to this genus. 
38. Monta? carrnata (J. Morris) Dana.—Moderately thick ; very inequilateral, 
oblong, height rather more than half the length, narrowing much posteriorly, and rounded 
truncate behind. Sharply carinate behind, and flank flat, broad, and nearly straight. 
Lateral surface a little compressed, rugose, rugee somewhat undulating and irregular. 
Inferior margin slightly arcuate, (nearly straight,) and forming almost a right angle with 
the posterior margin; front margin arcuate.—Length 2-9 inches; height §°5 L.; thick- 
ness 33, L., or ;° H.; apical angle about 132°.—Plate 6, figs. 1 a, 6, one valve, exterior 
cast, natural size. 
Wollongong, District of Illawarra. 
This is a very strongly carinate species, with a rugose surface. The anterior part of 
the shell is about one-third the whole length. There is a distinct cardinal area, which is 
profound, and has a carinate outline. The flattened flank makes nearly a right angle 
with the lateral surface. 
Pachydomus carinatus, J. Morris, in Strzelecki’s New South Wales, p. 273, pl. 11, fig. 3. 
Cypricardia rugulosa, Exped. Foss., Amer. Jour. Sci., ii. Ser., iv. 157. 
39. Maonra FRaGitis (Dana).—A sharply carinate species allied to carinata. 
Plate 6, figs. 2, 3, different specimens much broken, natural size. 
Glendon, valley of the Hunter. 
This large species is so much compressed and distorted that it cannot be properly 
characterized. The length is about 43 inches, and height 23. It has an acute or sub- 
acute carina, situated like that of the rwgwlosa. The surface is very coarsely and un- 
evenly marked with concentric strize or ridges, and the lines of the flattened flank make 
