24 
fair size and rectaiig'ular, and the cardinal margin longer than one wonld 
suspect from Morris’ illustration. If the figure of the Queensland sjiecimcn 
(hy one of ns) already quoted does not represent a portion of the “ Hat ” 
valve, then it cannot he 1). linupformis. 
The auricles of the convex valve were costo-radiate, again judging by 
Morris’ figure, and crossed by iinmeroiis lamina^, rendering the surface 
decussate. 
The inequality of the valves is shown, not only by this unequal degree 
of convexity, hut also by the projection of the umbo of the convex valve over 
its cardinal margin (PL X, Tig. 3), that of the concavo-convex, or at times 
almost plano-convex valve being insignificant. 
One of the most important features, spccilically of D. limcef ormis, is 
the oblique depression from the umbo downwards on one side of the convex 
valve (PI. XI, Pig. 1) ; this possibly represents the posterior end of the 
valve. 
The adductor impression of the “ flat ” valve was centrally situated, 
but nearer to the cardinal than the ventral margin ; it appears to have been 
jiitted for extra muscular attachments. The umhonal region also bore 
similar depressions for the insertion of supplementary muscles. 
Localities and Horizons . — Ilavensfield {T. Broion ). — Permo-Carbon- 
iferous — Lower Marine Series. Eoniaderry Quarry, Xowra [F. Mitchell) ; 
AVarragamha Ptiver, near The Peaks, Eurragorang ; Maria Island, Tasmania ; 
Mt. Eritton Gold-held, Queensland {F. X. Jack). — Permo-Carboniferous — 
Upper Marine Series. 
Collections . — Mining and Geological Museum, and Australian Museum. 
Deltopecten illawaurensis, Morris, sp. (?) 
(Plate Tl, Pig.'^. 2 and 3.) 
Peefen Tllawarcnsis, MoitIs, sti'zleoki’s Phys. Ileso’Ip. N. S. Wales, Ac., 18 In, p. 277, 
t. U, f. 3. 
Ohservaiions. — Morris figured a portion only— about one half — ’of what 
looks like n JUd valve, said by him to he “ depressed,” with sixteen prominent 
rounded costa.', the intercostal sj)aces broader than the latter, and the “ ears 
small,” but only one is shown in the figure. 
