152 Fossils from Australia. 
served cast, only a small portion of the original shell remains, from 
which it appears that ~~ beaydti was smooth, and marked only by faint 
lines of growth. cera 
pentagon and concentric. Two of the specimens are Ain of ils exte- 
rior, and the other is a calcareous petrifaction. As the last mentioned 
is quite solid, having the oblique cleavage of many calcareous fossils, 
(the spines of Echini, &c.) it is evident that the original was solid, an 
could not have been a Porpita, which one of the specimens somewhat 
resembles. And since, besides, there is no appearance of a mouth or 
any opening, or organs of motion, and the form varies very much, w 
may infer that the fossils were an internal secretion probably of some 
mollusk, and more allied to the cuttle-fish bone than any thing else we 
can suggest. The sot species here described has much the appear- 
ance of a Spatan 
8. Pentadia boat us.—Form pentagonal or approximately twelve- 
sided, suborbicular, with five broad and rounded folds (one largest) 
radiating from the centre. ‘The concentric pentagonal markings have 
the five angles at the centres of the triangular sections; and at the cen- 
tres of four of the sides of the pentagon, a is a reéntering angle.— 
Diameter 2 inches; thickness 4 inch.—Jllawarra. 
_9. Pentadia reniformis.—Resembles a vie segment of the prece- 
ding, with a broad lateral wing-like prolongation, nearly as large as the 
segment. It is quite thin, and its sha ape is reniform, though somewhat 
arcuately flexed. ‘The specimen is undoubtedly a perfect peruse 
ect # inch; breadth 14 inch; thickness 1 line.—Jddawarr ; 
. Penta din trigona.—Shape triangular, slightly sib flexed. 
Pg is thicker than either of the prece ing, and has a rounded m margin. 
It resembles the last in its markings, having the same angle of inter- 
section (that of a pentagon) between two sets of parallel Hage 
Breadth 1 inch; thickness 4 inch.— Illawarra. 
ll. ta.— Quite small 7 broad ovate, acute at besik; 
‘in not at all truncate; valves thin, very convex ; surface smooth 
with faint concentric lines of ag wth. 2. —Ditiensions; fort he beak to 
the opposite margin § of an inch; transverse line a fourth less.—Very 
near the L. lata of Murchison, (Sil. Rysiy pl. 8, fig. 11,) but not at all 
= squarish, ”__ Tlawa 
12. Terebratula aovgindatle Ob lois ovate, attenuate above, thickest 
about the centre, valves about equally and regu larly convex, infec r 
margin arcuate, ventral valve very regularly ovate in outline; bea 
flexed close to apex of ventral valve; aperture round and rather es 3 
line of junction of valves in side view almost straight, very slightly bent 
above, the cardinal edges being little concave ; surface smooth with a 
few concentric folds and some faint radiations.—Cardinal angle 82°; 
height 14 ssi breadth +47; H.; thickness #49; H. Near the T: haw 
tata.—Illawar 
13. Terebratula elongata.—( Verneuil, Paleozoic Rocks of Russia, 
p- 63, pl. ix, fig. 9.)—Scarcely eters from this species as described 
and hesrod by Verneuil.—Tlawar 
