41 
Permian Productinae and Stropiialosiinae of W.A. 
are Strophalusias. Tliey show the same strueture and arran^'ement of the 
musele scars in the brachial valve, and the impression of dental callosities 
may be seen on the casts. The s])ecimens do not show an ar(‘a, but until 
specimens with some shell preserved are seen it is impossible to say that its 
absence is not due to tlnckening' of the hin^'e-line behind the area. If no 
area is present then Bi'iui.rionia must be rei>‘arded as an altaclu'd form or 
of a line of attached ProcUudids with conse((uent muscle niov(*ment as in 
Strophalosia. 
IJetf^ralosia Kin<>' (IIKIS, ]). 27H) with genatyi)C IT. slocoitu Kino; is dis- 
tinguished from Stropitalosia s.s. by the possession of a non-spinose brachial 
valve. It seems doubtful whether a division of the Strophalosias based on the 
ornamentation of one or the other \'alve is of great advantage, and although 
of the s})ecies here described S. etheridgei and gerardi (?) would be ])laced 
in Ileteralosia 1 have left them in Strophalotiia s.l. If King’s division is 
accepted, a new genus, without spines on either valve, must be proposed to 
include S. clarkei and kimherleyensis. 
Strophalosia cf. Strophalosia beecheri K’owley. 
IM. Vj tigs, l-.'i. 
isn.‘h — Sh'o; lialo.s'ia brrchfvl Kowley, ]). 308, ])1. 14, tigs. 18-19. 
\\H)S~~Stro/)haliosi(i hcrclieri Kowley, ]>. 70, pi. 17, tigs. 24-25. 
1914. — Sirophalosia hccchcri KoAvley, Weller, ii. 140, pi. xix, tigs. 37-38- 
Material. — U.W.A. 20449, one s})ecimeU" -conjoined valve; Waltliarrie Pools, 
Wooramel River District; Callytliarra Liinestoii(‘. 
Ddtgnosiy . — Shell small, almost circular in outline, hinge-line slightly less 
than greatest width of shell. Surface oiiianumtation of ei'(!ct s[)ines of 
approximate (luim-umual arrangement and tine growth lin(‘s. 
Pedi(*Ie vahe convex, asymnudric without sinus though flaitened medially 
and sloping stt'eply anteriorly aiul latei'ally. Cicatrix large, placed on one 
side of umbo. Area as long as hinge-line, Hat and trianguhu’. Pseudo- 
deltidium triangular. Ttadh short and diverging. 
Brachial valve concav(g area distinct, almost as large as that of [)edi(de 
valve, pseudo-cliilidium larg(' and triangular. 
internal features not known. 
Descriptio}! : Dimensions of Bpeeimen, 
Height l*2.r> 
Maximum breadth .. .. 12.(i 
Length of hinge-line . . . . 8.8 
Specimen too crushed to give accurate measurcmient of thickness. 
The pedicle \-alv(‘ of this specimen is asymnudric du(‘ to the largo cicatrix 
of attachment on on(> side of the umbo. It is evenly swollen in tin* middle 
wiih the sides and the front sloping steeply giving it a somewiiat s(iuashed 
appearance. The ears are small and tint with (d)tuse cnrdinal angles. The 
specimen is iinl'ortunately badly weathered so that the ornamentation is 
ol)scured. Slender erect si)ines with ai)proximate (piincuncial arrangement 
are the obvious feature of the ornamentation, rhe concentric shell laminae 
<d‘ the original slu'll surface, if these Avere prt'sent, being ()bs('ured. The 
