Permian Productinae and Strophalosiinae of W.A. 
IT 
by large costae, variable in width, bearing large spine bases; these show 
no regular arrangement. The costae tend to approach and disappear in the 
sinus. Two large spines are on the ears and three on the flanks just above 
the angle separating the ears. There is no enlarged rib or hollow on which 
they are placed. The umbo is rounded and barely overhangs the hinge-line. 
The ginglymus, if present, is obscured by matrix. 
Variation within the species. — Owing to the paucity of specimens (5) 
it is impossible to determine the limits of variation. 
Comparison with other species. — This variety differs from D. callythar- 
rensis in the shape of the ears (here continuous with the anterior margin 
but in D. callytharrensis distinct and joining the lateral margin about halfway 
down the flanks), the greater convexity of the flanks and the invariable 
appearance of a well-marked sinus in the pedicle valve. The folds, too, in 
this species are enlarged costae and not formed, as in D. callytharrensiSj by 
two or more costae coalescing. In all these particulars they approach P. 
indictis AVaagen, but continually differ in the much finer ornamentation. 
It is possible that this form should constitute a distinct species, but in 
the absence of any definite knowledge of their stratigraphical relations to 
D. callytharrensis I have preferred to designate them as a variety. They are 
obviously closely related to I), callytharrensis mihi. 
Dictyoclostus gratiosus (AVaagen). 
PI. ii, figs. 5-7. 
1884. — Producius gratiosus AVaagen, p. 691, pi. Ixxii, figs. 3*7. 
1893. — Prodiictus gratiosus AVaagen, Rothpletz, p. 76, pi, x, fig. 15. 
Idld.—Productus gratiosus AA^aagen, Broili, p. 12, pi. cxvi, figs. 4, 5, 7-13. 
1927. — Prodiictus gratiosus AA^aagen, Chao, p. 44, pi. iv, figs. 6-10. 
1928. — Producius gratiosus AVaagen, Hamlet, pp. 19, 20. 
21aterial. — Aus. Mus. 
F 37567 — Vi mile east of shale outcrop, Minilya River, North-AVest Division, 
Wandagee Stage. 
F 37568 — 14 mile west of shale outcrop, same locality and horizon. 
F 37569-37571 — Bank of Minilya River, same locality and horizon. 
Diagnosis . — Shell small to moderate in size, outline hexagonal. Pedicle 
valve inflated, geniculate; brachial valve concave. Greatest width at hinge- 
line, ears small and pointed. 
Pedicle valve with flat visceral disc, shell geniculate. Ornamentation 
reticulate on visceral disc, costate on trail. Strong sinus. Small erect spines 
scattered on trail and alar extremities. Costae converging towards sinus. 
Brachial valve concave with median fold. Ears excavated, smooth or 
lightly costate. Convergence of costae toAvards fold. Valve with reticulate 
ornamentation on posterior part of shell. 
Internal characters not knoAvn. 
Description. 
Dimensions. 
Length of hinge-line 
27-8 
18-0-h 
16-6 + 
25-0 
14‘5-h 
Height 
Curvilinear length of pedicle 
17-7 
13-7 
16*1 
15-8 
11*7 + 
valve 
30*9 
21-0 
32*3 
31*8 
21-0 
