K. L. Prexdergast. 
4() 
The pedicle valve is flatly convex, the maximum convexity behind the 
umbo, thence flattening gradually to the anterior and lateral margins and 
steeply to the cardinal margin. The area is short, equal in length to half the 
maximum width of the shell ; it is relatively high with a very narrow, ahnost 
straight-sided pseudo-deltidium. The area of attachment is large, and has 
the appearance of callus over the shell surface. The ornamentation of the 
pedicle valve is essentially spinose, the spines adherent, Avith an irregular 
quincuncial arrangement. The structure of the shell surface is lamellar though 
the lamellae are largely obscured. 
The brachial valve is concave. It slopes steeply from the umbo to the 
middle of the shell, thence folloAving the curve of the pedicle valve. The shell 
structure is lamellar, but the valve is Aveathered, and no spine bases are seen, 
the ornamentation consisting of the truncated lamellae and irregularly spaced 
nodules. The area of the brachial vah’e is narroAV but distinct. Internal 
features not shoAvn. 
Dimensions. 
Height .. .. 30.4 
Maximum breadth . . . . 38 
Thickness .. .. 10.8 
Etheridge says (1880, p. 296) that he finds “what appears to be the bases 
of insertion of spines’’ on the brachial A’al\'e of King’s type specimen. It 
is difficult to come to a decision on this point from a study of the type speci- 
men alone as, although there are holloAA^s and small prominences on the 
lamellae, it seems almost impossible to decide that these prominences are or 
Avere spine bases. They shoAV no concentric structure and no sign of aperture. 
It is noticeable, hoAA'ever, that Avhere the spine bases are Avorn down on the 
l)edicle Auilve, they, too, show no structure. On his figures of the Queensland 
specimens, too, Etheridge figures no specimen Avith spines on the brachial 
valve. 
Strophalosia sp. cf. Str. gerardi King. 
PI. V, fig. 14, 15. 
Maicrial. — F.W.A., 12399. One pedicle valve. Fossil Cliff, Irwin RKer. 
Fossil Cliff horizon. 
Description . — The shell is convex, non-geniculate, Avith the greatest con- 
vexity in the visceral region l)ehind the cardinal margin. From this area of 
maximum convexity the surface slopes gradually to the anterior and pos- 
terior margins, but more steeply laterally. A large cicatrix covers the 
uml)onal region. The ai'ea is concave Avith a Avell-marked pseudo-deltidium, 
at the base of Avhich arise strong diverging teeth. The length of the area is 
about half the maximum l)readth of the shell. 
Dimensions. 
Maximum Avidth 
31.7 
Length of hinge-line 
. 15.3 
Height 
27.0 
Length of pedicle A-alve 
. 38.9 
The shell surface is lamellar Avith strong olfiique spines arranged in 
irregular concentric roAA’S. Posteriorly ami on the cardinal slopes the spines 
are small and adherent; they become larger toAvards the anterior margin. 
