42 
K. L. Prendergast. 
area is flat and lies in the plane of the commissures; it is interrupted by a 
triangular slightly convex pseudo-deltidium. Owing to the crushing of the 
brachial valve, rhe teeth are seen to be short, stout and diverging. 
Even in its uncrushed form, the brachial valve must have been very 
concave. The ornamentation cannot be seen at all unless some pits due to 
■weathering indicate that it was spinose. The area of this valve is as large 
as the pedicle area, with a well-develoi>ed pseudo-chilidium. 
Comparison n'itJf other species. — This specimen resembles Strophalosia 
heecheri Rowley (Weller 1914, p. 146, pi. xix, flgs. 37-38). Weller, in his 
description of this species, quotes its asymmetric character as a diagnostic 
feature. From his flgure 37 it Avould appear that in that species, as in this 
specimen, the asymmetry is probably due to the cicatrix on one side. It is, 
however, a broader form than the present species and Weller says broader 
than long: but as he, too, had only one specimen, the variation within the 
species is not known. 
Bemarhs. — This specimen has been compared to Strophalosia heecheri^ 
but not identifled finally as a member of that species since further specimens 
are required, both from America and Western Australia, before any definite 
identification is possible. More specimens, too, may establish the present 
specimen as a member of one of the variable Western Australian species. 
Strophalosia clarkei (Etheridge). 
PL V, fig. 4. 
l^'i'I.—Productus clarl-ei Etheridge, p. 334, pi. xvii, figs, 2, 2a, 2b; pi. xviii 
figs. 4, 4a. 1 , ^ , i , 
1877. — ProduePns clarl-ci Etheridge, de Koninck, p. 203, pi. x fio-. 5 * -.q xi 
fig. 3. X , 1 , ^ , i . , 
1878. — ProducUis eJarhei (Etheridge), Etheridge, jun., p. 51. 
1880. — Strophalosia rJarl'ci (Etheridge), Etheridge, inn., p. 289, pi. ix, figs. 
18-21; pi. X, figs 22-28; pi. xi, figs. 29-31; pi. xii, figs. 32, 33. 
1892. — Strophalosia clarhei (Etheridge), Etheridge & Jack, p. 258 pi. xiii, 
figs. 12-17; pi. XIV, fig. 19. ’ 
Iloloti/pe, helonged to Daiiitree Collection. Present, location of type specimen 
not known. 
Other Material. — B.Al. B 5885, Capertree, N.S.W. (figured by Etheridge 
1880). Ans. Mus. F 36234, 36235, .liniba Jiniba. near Mooka Springs, North- 
West Pivision. Gascoyne series. 
Diagnosis. — Shell transversely oval to subquadrate, hinge-line less than 
greatest shell width. Pedicle valve inflated, without median sinus. Brachial 
valve fiat to concave. Ornamentation of silky laminae on both valves. 
Interior of pedicle valve with thin median ridge sti.arating dendritic 
adductor muscle impressions. Diductors large, fiabellate and longitudinally 
striate. Teeth large. 
Brachial valve with strong cardinal process continued into long median 
septum. Dental sockets large and oblique. Adductors high in valve. Brachial 
impressions .strong, folloAving edge of valve; valve geniculate with marginal 
rim perpendicular to visceral disc. Line of three depressions (adductor scars, 
depression below muscle scars and ends of brachial impressions) on each 
side of median se]>tum. 
