258 
Genus— STBOPIIALOSIA, King, 1844. 
Ann. and Mag. Nat. Hist., 1844, xiv., p. 313; Mon. Permian Foss. England, 1850, p. 93.) 
STHOPniT.osiA Claekei, Eilieridge, sp. 
PI. 13, figs. 12-17 ; PI. 14, fig. 19. 
Products Clarkei, Etheridge, Quart. .Journ. Geol. Soc., 1872, xxviii., p.334 t. 17, f. 2 and 2a-5, t 18 f. 4-4a.. 
„ „ He Koninek, Foss. Pal. Nonv.-Galles du Snd, 1877, Pt. 3, p. 203, 1. 10, f. 5, t. 11, f. 2. 
„ „ Etheridge fil.. Oat. Australian Foss., 1878, p. 61. .. n f f in 
Strophcdosia darjcci, Etheridge fil., Proc. K. Phys. Soe. Edinb., 1880, v., p .289, t. 9, f. 18 - , . 
f. 22-28, t. 11, f. 29-31, 1. 12, f. 32 and 33. 
,, TroocZifj, Davidson (ms.) 
Sp. Char. Shell rotimdate-quadrate, ventral valve strongly 
inflated ; prominent and convex ahout the visceral region, sloping gra ua y o o le 
front, but non-geniculate and unproduced. Ilinge-line straight, ut no equa o 
width of the shell. Ears flattened, small when compared with the general proportioms 
of the valve. Beat large, short, and blunt, hut not overhanging t e nnge ine , 
diately under it are two large, obliquely placed teeth, which fit into tie soc e s o i 
dorsal valve. In the umbonal region of the shell, proceeding from the beak Awards 
the front, is a fine ridge or septum (a groove in casts) with, on each side of it, 
dendritic adductor muscular impressions, each bounded on its outer margin " 
defined groove (ridges in the cast). Immediately in front of these adductor '>^P™ssi^: 
isalargebluntprominence (which in the cast becomes a hole or ossa o var^n„c ep > 
of a very marked character), with the outer edge much less precipitous than the m • 
On each side this prominence are the depressed scars of the cardinal museks, much deeper 
and more impressed on their inner or umbonal margins, and gradually dy ing out laterally 
towards the sides of the valve; they arc vertically grooved and ridged. (In the ca 
these impressions become ridged prominences, projecting or scarp- i e a on,, eir 
edges, and they impinge somewhat on each side over the deep fossa ]ust described^ 
The interior snrface of the valve is pitted and ridged, producing, in the cast, 
and grooves ; the former are continued over the surface of the blunt prominence (fossa 
in the cast) ; the ridges seen on the interior represent the decurrent bases ^ _ 
The exterior surface is comparatively plain, with fine, vertical, wavy lines, pr j 
from which are occasional slender spines. • , n i + 4i,r 4rnm the 
The dorsal valve is square, oval, flat, and very thick, bevelled ^ 
interior on the front margin. The latter is apparently continuous, and 
any way. Hinge-line with rounded alar angles; area well marked, , f 
Cardinal boss thick, strong, and prominent, projecting from the hmge-lme at an ang 
119°, with the exterior plane of the valve centrally divided by a 
flanked on each side by a kind of shoulder. Sockets for the reception of the 
ventral valve, deep, broad, and so far surrounding the boss a^s to produce an appea^n 
of isolation in the latter from the remainder of the valve. The cardma bos^^^_ 
supported on each side by indistinct, oblique, alar ridges. Septum strong and u 
like, extending for more than two-thirds the distance between the cardina os ^ 
front margin, sometimes terminating in a small button. j^uated 
is a deep depression, divided in the middle line by the septum, and in wine ^ 
the dendritic adductor muscular impressions. This ^‘'^VdenressioD 
transverse ridge running across the valve from a second heart-shaped depr® 
similarly divided by the septum. The reniform impressions are aecp 
much incurved, and abrupt at their front termination, and bounded ^ge is 
groove or linear depression following their course The internal bevelledjdg^ 
marked with very fine granules of pustules and small vemings, being the in 
