154 Fossils from Austraha. 
Cuzoets, (nov. gen.)—Shell inequivalve, inequilateral, thick, trans- 
verse subovate, closed (or near ly so.) Beaks large, salient and incurve 
Posterior margin broadly rounded ‘and a little dilated? Ligament in- 
ternal. Hinge line flexed to one side at middle and passing beneath 
the lower of ib beaks. Valves thin. Surface marked unevenly with 
regular concentric stria 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 ineurved, 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 hg less than a line ina large 
species measuring seven inches in lengt 
19. Cleobis grandis. —Thick, very convex, right valve ye ; front 
very abrupt; anterior soph about one-third the whole length ; inferior 
oO 
apical angle 105° —Idlawarra. 
20. Cleobis gracilis. —Resembling C. grandis, but more projecting 
anteriorly ; anterior Rertion; about two- fifths the whole length.—Length 
es; height 72; L; thickness 7%% L; apical angle 126°.— 
Tr arra. 
Cleobis ? recta.—Subelliptical, somewhat compressed ; lateral 
at flattened; marked with concentric lines of growth; inferior 
peryin straight at middle, parallel with dorsal ; postoro: doesnot argin 
uch dilated. —Length 34 inches; height probably 485 o. L; thickness 
The straight lines of growth over the medio-lateral surface, 
aod straight medio- inferior margin give a peculiar character to this 
apeci es.—Jllawarr 
‘a 
| 
Me —Transverse, very nearly equilateral, anes 
evenly sy delicately marked with deep concentric strice in 
of the valves crenulate within; large —_— muscular aes a 
little exc panies transverse and ‘suboval ; maller anterior excavate, ob- 
long; parnner rather faint; palleal i impression faint but distinctly with- 
out a sinus, and quite reaching. the anterior sey eke impression ; sur- 
face of cast wer —Length 2 inch; “height 2 8%, L; thickness 7% L; 
anterior part => of the whole length ; apical angle e 140°. The impres- 
sion of iwo divergent teeth is finely preserved.—I/lawarra. 
The following species have the entire palleal impression, two ante- 
rior a and one posterior muscular impressions, and the external ligament 
of Astarte. Yet the form is more transverse and smocullaseral than is 
characteristic of = genus, and the ligament is iy occupying the 
whole cardinal a The beak of an interior cast has the summit ob- 
liquely truncate, je the lateral surface just posterior vr middle is more 
or less flattened. The large muscular impressions are broad sub- 
st 
terior surface is concentrically striate. The valves at middle are quite 
~ hardly 45 of an inch in the first of the following species, and 
‘thicken below towards the margin, where the same species 1s 
