14. Productus fragilis.—Subquadrate, with front angles rounded, rather broader than long, hinge line straight, nearly of the breadth of the shell, front straight, upper valve very convex, irregularly longitudinally striated, with some concentric plications, sometimes with occasional rudiments of spines, front and sides rather abruptly reflexed; beak small, projecting but little below the hinge line, and the apex not much inflexed.-Length of hinge line 14 inches; depth of concavity below, over half an inch.-This species is very unlike the bra chytherus in its less prominent beak and longer hinge line. It is near the rugosus, but is much thicker and more convex above.-Illawarra. 15. Solen (Solecurtus?) ellipticus.-Shell very slightly convex, very regularly elliptical, with no trace of a beak, breadth little less than half the length, anterior part rather more than one-third the whole length; smooth with fine scarcely apparent concentric striæ, superoanterior margin slightly depressed, and perhaps two or three faint radiations from the hinge over the lateral surface (apparent in the cast of the under surface of the valve, but not of the upper); cast of the hinge showing no teeth though apparently perfect-Length 1.4 inches; height L.-Illawarra.

8 100

16. Solen (Solecurtus?) planulatus.-Shell flat except a slight bending over the postero-dorsal portion; no beak, elliptical in outline with the inferior and dorsal margins straight, and the anterior and posterior extremities of equal breadth; breadth more than half the length; surface smooth with some faint concentric undulations and lines of growth, apparent especially near inferior margin; no palleal or mus cular impressions visible.-Length 13 inch; height L.-Harper's Hill.

17. Pholadomya undata.-Nearly or quite equivalve, oblong transverse, subelliptical; beak projecting but little; thinning to an acute edge in front, prolonged and narrowing somewhat behind; sides flattened, posterior surface from the beak to the posterior angle obliquely truncate and exteriorly subcarinate; cardinal area linear, circumscribed; surface with a few irregular obsolescent longitudinal plicæ or undulations, smooth, crossed, especially below, by faint radiations.-Length 3 inches; height 5 L; thickness L; distance of summit of beak from anterior margin L; apical angle 138°; projection of beak above cardinal margin one-eighth of an inch.-Illawarra.

59

33

100

18. Allorisma audax.-Transverse, very inequilateral, left valve largest, front very broad and flattened, and having a narrow area adjoining the margin extending down from the beaks which is a little concave; posterior prolonged and much compressed, narrowing and somewhat recurved, gaping; beaks very large and prominent, incurved, contiguous; lateral surface anterior to middle strongly flattened, or even concave; surface unevenly plicate and having some faint radiations laterally and posteriorly, plications large rounded and smooth, the alternate mostly becoming obsolete towards middle of lateral surface.

63 100

Length 44 inches; height 6 L; thickness L; the beaks are much more prominent than in the A. curvatum, the posterior extremity much narrower, the flank less inflated, and the front more abruptly truncate.-Illawarra.

SECOND SERIES, Vol. IV, No. 10.—July, 1847.

20

CLEOBIS, (nov. gen.)-Shell inequivalve, inequilateral, thick, transverse subovate, closed (or nearly so.) Beaks large, salient and incurved. Posterior margin broadly rounded and a little dilated. Ligament internal. Hinge line flexed to one side at middle and passing beneath the lower of the beaks. Valves thin. Surface marked unevenly with regular concentric striæ of growth and without radiations.-This genus appears to be near the Ceromya of Agassiz; but of this we cannot be certain, as the palleal and muscular impressions are not visible. There is much external resemblance to the Avicula cuneiformis of Verneuil, (Russia, pl. xli.) The beaks are prominent and incurved, but are not flexed at all forward; they project over or overhang the cardinal line, the summit being separated from it by an intervening space. The valves are quite thin, the thickness being less than a line in a large species measuring seven inches in length.

19. Cleobis grandis.-Thick, very convex, right valve largest; front very abrupt; anterior part about one-third the whole length; inferior margin regularly arcuate; surface concentrically striate and a little undulate. Length of large specimens seven inches, height 6L; thickness L; apical angle 105°-Illawarra. 100

20. Cleobis gracilis.-Resembling C. grandis, but more projecting anteriorly; anterior portion, about two-fifths the whole length.-Length 2.9 inches; height L; thickness L; apical angle 125°.— Illawarra.

21. Cleobis? recta.-Subelliptical, somewhat compressed; lateral surface flattened; marked with concentric lines of growth; inferior margin straight at middle, parallel with dorsal; postero-dorsal margin much dilated.-Length 34 inches; height probably 1% L; thickness To L. The straight lines of growth over the medio-lateral surface, and straight medio-inferior margin give a peculiar character to this species. Illawarra.

22. Astarte gemma.-Transverse, very nearly equilateral, surface evenly convex, delicately marked with deep concentric striæ, margin of the valves crenulate within; large anterior muscular impression a little excavate, transverse and suboval; smaller anterior excavate, oblong; posterior rather faint; palleal impression faint but distinctly without a sinus, and quite reaching the anterior muscular impression; surface of cast smooth.-Length inch; height L; thickness L; anterior part of the whole length; apical angle 140°. The impression of two divergent teeth is finely preserved.-Illawarra.

The following species have the entire palleal impression, two anterior and one posterior muscular impressions, and the external ligament of Astarte. Yet the form is more transverse and inequilateral than is characteristic of that genus, and the ligament is longer, occupying the whole cardinal area. The beak of an interior cast has the summit obliquely truncate, and the lateral surface just posterior to middle is more or less flattened. The large muscular impressions are broad subelliptical or suborbicular, with the upper side often straight. The smaller anterior is situated under the beaks as in Astarte. The exterior surface is concentrically striate. The valves at middle are quite thin, hardly of an inch in the first of the following species, and they thicken below towards the margin, where the same species is

half a line thick. Although we have not yet made out the teeth of the hinge, we propose to describe the species under the generic name Astartila.

23. Astartila intrepida.-Thick, somewhat transverse, neatly but somewhat unevenly concentric striate; anterior part about the whole length. Anterior muscular impression excavate; smaller subquadrate or a little oblong; larger marked with a number of fine vertical striæ on the lower posterior quarter; antero-lateral surface of the interior with two parallel flattened areas, the one adjoining the muscular impression convex, (concave in the cast.)-Length 13 inch; height 80% L; thickness L; apical angle about 120°.-Illawarra.

100

24. Astartila cyprina.-Thick, transverse, length more than one third greater than height; palleal impression very distinct, inner surface of valve very minutely rugose, below palleal impression radiately subplicate; posterior muscular impression not excavate, crossed vertically by a fold; large anterior deeply excavate, convex, crossed by a few faint vertical lines, which are closer towards the posterior margin; smaller somewhat excavate, oblong sigmoid. Cast with antero-lateral surface simply a little flattened.-Length 2 inches; height thickness L; apical angle about 118°.-Illawarra.

58

L;

25. Astartila cytherea.-Thick, slightly longer than the height; inner surface smooth, palleal impression rather faint; posterior muscular impression large and very distinct, very slightly excavated, not intersected by a vertical fold; larger of the two anterior deeply excavate, the excavation deep and very abrupt on the upper side, four or five striæ crossing the muscular impression vertically near posterior margin; smaller anterior oblong sigmoid, but not excavate. Cast with anterolateral surface simply somewhat flattened.-Length of cast 14 inch; height L; thickness L; apical angle 1120.-Illawarra.

26. Astartila polita.-Rather thin, somewhat transverse; surface smooth and shining, with faint lines of growth; muscular impressions scarcely excavate and palleal impression faint; the larger anterior very even and without vertical striæ or plications; a slight fold in the surface just anterior to posterior muscular impression, and a smaller one crossing this muscular impression. Cast with antero-lateral surface simply very slightly flattened.-Length 1 to 13 inch; height 7 L; thickness; apical angle about 113°.-Illawarra.

27. Astartila cyclas.-Rather thin, slightly transverse; surface marked unevenly with concentric striæ; posterior muscular impression very distinct but hardly excavate, a fold in the inner surface of the valve just anterior to it; both of the anterior muscular impressions strongly excavate; the larger without vertical striæ; the smaller placed obliquely so that the cast of it is a linear trenchant ridge; palleal impression very distinct, somewhat plicatulate. Cast with summits of beaks quite thin, the lateral surface strongly flattened, and another flattened area adjoin. ing anterior muscular impression.-Length 13 inch; height L; thickness L; thickness of cast L; apical angle 135°.Illawarra.

45

100

90

100

28. Astartila transversa.-Thick, transverse, length full a third greater than height; posterior muscular impression faint; crossed by a fold vertically, and another more distinct in the surface just anterior to

73

the muscle; large anterior somewhat excavate, without vertical striæ, small anterior obliquely excavate; palleal impression not very distinct. Cast with antero-lateral surface of beak strongly flattened in two parallel planes, that adjoining the anterior muscular impression a little concave. -Length of cast 1 inch; height L; thickness L; apical angle of cast 105°, of shell about 115°. This species has two parallel flattened areas on the lateral surface like the intrepida and cyclas; but its form, the absence of vertical striæ from the anterior muscular impression and other characters distinguish it.-Illawarra.

100

Genus CARDINIA, (Ag.)—Form of the species below-described, transverse, and dorsal margin more or less convex without a salient beak; two strong anterior muscular impressions, and one posterior less distinct, the smaller anterior linear, and situated vertically on the front; the palleal impression entire, and not quite reaching to the anterior muscular impression. No cardinal area to the shell, but a strongly defined one to the cast of the interior. The species differ from Cardinia in having the lateral surface posteriorly marked with radiations; the front of an interior cast is strongly truncate, and the flat truncate surface extends on and separates the anterior margins of the large anterior muscular impressions from the medial line; the cardinal areas in the cast are very long linear, and but slightly widen posteriorly. We refer the Orthonota? costata, of Morris, to this genus.

29. Cardinia recta. Very inequilateral, narrowing much posteriorly, length 24 times the breadth, dorsal margin a little convex, inferior straight at middle; lateral surface not depressed, marked with concentric striæ and faint radiations, these radiations producing slight undulations in the lines of growth; palleal and posterior muscular impressions very faint, both of the anterior strong, a convex linear area adjoining the larger extending upward. Interior cast having a very neat, narrow and quite flat cardinal area, with the dorsal margin prominent; lower edge of the cast very thin; surface quite smooth with faint radiations.-Length 2 inches; height; thickness L; apical angle 125°. The cast resembles much Verneuil's Solemya primæva, pl. xix, fig. 5.—Illawarra.

30. Cardinia cuneata.-Very inequilateral, length about twice the breadth, diminishing posteriorly, and thinning below; superior margin arcuate, interior strongly concave just posterior to middle, and lateral surface depressed; palleal impression distinct; anterior and posterior muscular impressions excavate. Cast with cardinal areas concave and separated from lateral surface by a strong carina, very long, extending to posterior margin.-Length of cast 1 inch; height L; thickL; apical angle of cast 110°.-Illawarra.

ness

Genus PYRAMUS, (nov. gen.)-Equivalve, somewhat inequilateral, transverse, elliptical, with the front and posterior margins nearly alike, entirely closed; beak somewhat prominent. Ligament external. Palleal impression entire, distant from the margin. Three muscular impressions to each valve, two anterior and one posterior; the larger anterior, suborbicular, smaller anterior, facing the same way with the larger, and situated just above its upper angle; posterior faint. Surface marked with concentric lines of growth. Cast of summit of beak a slender point. Shape nearly of Donacilla and Sanguinolaria, but it differs in its entire palleal impression, and has also two anterior muscular im

pressions which belong together, to each valve, as in Corbis. From the impression of the hinge of a left valve, there appear to be no prominent teeth; it has a very oblique shallow sulcus, directed posteriorly from the centre of the hinge, and a slight excavation anterior to the centre. The form is more transverse and the teeth less distinct than in Corbis. It has not the long lunate muscular impression of Lucina.

31. Pyramus ellipticus.—Oblong, length half greater than breadth, lower margin arcuate, sides evenly convex, surface strongly but unevenly marked with regular concentric striæ, posterior and large anterior muscular impressions rather indistinct, not excavate; palleal impression perceptible and posteriorly plicatulate. Cast of beak acute at apex.-Length 13 inch; height 7 L; thickness L; apical angle 137°. Another specimen, probably same species, three inches long.Harper's Hill.

41

32. Pyramus myiformis.-Oblong, length two-thirds greater than breadth; exterior smooth, with faint striæ of growth; lower margin nearly straight, lateral surface below somewhat flattened; muscular impressions distinct, posterior not excavate, large anterior a little so above, smaller anterior deeply excavate, and the surface of attachment facing the same way with the larger; palleal impression faint. Cast having the beak terminate in a minute cylinder, and having the lateral surface, from the summit obliquely downward and backward, depressed. -Length 2 inches; height L; thickness about L; apical angle 148 or 150°. The front and posterior margin are more broadly rounded than in the preceding, the lower margin straiter, the apical angle much larger.-Illawarra.

33. Nucula abrupta.-Thick, elongate, transverse, rather abruptly narrowing behind the summit, and diminishing posteriorly; posterior dorsal margin much concave; anterior margin rounded; cast strongly carinate from the beak to the posterior angle, and having a wide and flat cardinal area; palleal impression distinct, somewhat excavate, smooth; anterior muscular impression somewhat excavate, smooth; posterior strongly excavate in the upper part, (in the cast it lies around the posterior carina, and the upper extremity forms an abrupt angle on the outline of the carina;) surface of cast smooth, some faint radiations hardly distinguishable.-Length 1 inch; height L; thickness or L; apical angle about 135°; height in the line of the upper part of posterior muscle, about half greatest height.-Illawarra. 34. Nucula? Harper's Hill.

40

35. Cypricardia rugulosa.-Oblong transverse, anterior part onethird whole length, narrowing rather abruptly from the beak posteriorly, posterior surface (flank) broad and flat truncate, with a carinate margin extending from the beak to the lower posterior angle; cardinal area distinct, profound; lateral surface marked with longitudinal striæ of growth, which are quite irregular or undulate, making a right angle (and in some parts a less angle) at the carina; also a few large obsolescent longitudinal folds.-Length 2.9 inches; height L; thickness L; apical angle 132°.-Illawarra.

33

55

100

36. Cypricardia sinuosa.-Oblong transverse, anterior part about whole length; posterior rather rapidly narrowing but not abruptly;