Permian Productinae and Stropiialosiixae of W.A. 
43 
Description. — Little can be added to the descriptions of this species in 
Etheridge (1880) and Etheridge and Jack (1892). The two specimens from 
Jimba Jimba are brachial valves whose external features are obscured by 
matrix. The internal features are as described by Etheridge. The charac- 
teristic structures of the valve are the line of three depressions (those of 
the adductor impressions, depression below the muscles and ends of brachial 
impressions) on each side of the median septum and the groove and marginal 
ridge on the outside of the brachial impressions. Inside the brachial 
impressions the shell is raised and prominent. 
C omparison with other specjes. — The differences between this species and 
Strophalosia himberleyensis mihi will be found under the heading of the 
latter species. 
Etheridge (1880, jn 290) suggested that Strophalosia gerardi King and 
Strophalosia clarhei (Etheridge) were possibly one and the same species. 
The absence of any I’eliably identified specimens of Str. gerardi showing the 
internal characters led him to postpone a final decision in the matter. The 
situation of Str. gerardi is still the same, but these species may be distin- 
guished by their external characteristics. Strophalosia gerardi has a relatively 
much shorter hinge-line, and its external ornamentation of obli(iue adherent 
s])ines on coarse concentric lamellae distinguishes it from the smoothly silky 
surface of Str. clarhei. Etheridge (1872) described the ornamentation of 
Str. clarhei as “covered with fine, vertical, wavy lines, projecting from 
which are numerous slender spines.” This ornamentation 1 have not seen, 
weathering having removed apparently both the vertical lines and the spines. 
However, the descrijition would certainly not fit the coarse adherent spines 
of Str. gerardi. 
Strophalosia etheridgei n. sp. 
PI. V., figs. 5-12. 
Sifnti/pcs, — O.S.W.A. 1/.T242 (a), creek, mile Avest of Callytharra Springs, 
Wooramd Piver. Callytliarra Limestone. 
Topol ypos. — G.S.’W.A. 1/5242 (b), same locality and horizon. 
OIhrr Mafcrial~V.\Y.A., 20267,’ Possil Cliff, Tnvin River. Pos.sil Cliff hori- 
zon. TT.W.A., 20247, Fossil Ridge, TrAvin River Pistrict. Fossil Cliff horizon. 
Alls. Allis. F 3SI6.3. 3S464, 38448, Wandagee Station, Alinilya River, North-West 
DiA’isioii. Wandagee stage. 
Diagnosis . — Shell small, thin, transversely-oval to almost circular in out- 
line. Hinge-line less than greatest Avidth. 
Pedicle valve flattish, evenly convex, non-sinuate, area relatively Avide 
wilh nari’OAv but not prominent ])seudo-deltidinm. Ornamentation of adher- 
ent spines interrupting .silky laminated surface structure. Umbo not promi- 
nent, area of aftachment small. Teeth small and diverging. ALiscle scars 
deltoid in outline, non-dendritic, almost under umbo. 
Brachial valve flat in visceral region Avitb upturned margins. Ornamen- 
lation of silky laminae and concentric Avrinkles. When Aveathered, valve pitted 
anteriorly. Cardinal iirocess inclined, continued into short median septum. 
Sockets prominent, inclined at high angle. Afuscle inpwessions rounded, at 
base of cardinal process. 
