Permian Productinae and Strophalosiinae op W.A. 
13 
and visceral disc; rows of spines on ears and cardinal slopes; diaphragm 
absent. Brachial valve concave or geniculate; marginal ridges prominent, 
extending along hinge. Hinge teeth and sockets not developed. 
Range, — Carboniferous and Permian. 
Remarks. — The diagnosis has been emended to include semireticulate 
productids with a ginglymus (see p. 9). The Western Australian, Timor and 
Indian species Avhich would normally be placed in this genus are sometimes 
found to have a ginglymus though agreeing in other particulars with species 
of this genus. Where the margin is interrupted by the cardinal process, the 
ginglymus is notched to give the “delthyrium,” into which the cardinal process 
fits, as previously suggested by Dunbar and Condra (p. 18). Below this 
notch and on each side, thickened ridges which gradually die out laterally, 
articulate with the transverse ridges of the brachial valve. As would be 
expected, the ginglymus is not seen if the two valves fit tightly, but is on1v 
exposed when the brachial valve is slightly displaced. This was proved in 
a specimen (S.M. No. 3604) of Dictyoclostus indicus (Waagen) from the 
Salt Range; it possessed both valves, and was without an area, but showed 
an internal groove in that position when the brachial valve was removed. 
The ginglymus has been noted in one other genus. Productortlns ot‘ 
Schuchert and Cooper (1932, p. 83). In Vroductorniis, Schuchert and Cooper 
believe that the ginglymus has arisen from the reduction of the area. In 
Productids it seems more likely that the area arose from the ginglymus. 
The Permian species of Dictyoclostus, as far as can be seen from a study 
of the literature, differ from the Lower Carboniferous species in the restric- 
tion of the reticulation to the posterior part of the shell, the separation of 
the ears from the flanks and the possession of an articulating ^^area.’’ 
The larger Western Australian members of the genus Dictyoclostus are 
undoubtedly closely related, probably in the same way as the spiralis- 
subcostatus grou]> of the Salt Range, and it is only lack of sufficient material 
which prevents the apjn’eciation of their relationships. 
Dictyoclostus callytl: arrensls sp. nov. 
PI. i, figs. 1-7, PI. ii, fig. 1. 
1903. — Troductns semireticulatus Martin, Etheridge, jun., p. 18, pi. ii. 
figs. 3-0. 
1907. — Produci-us semireticulatiis Martin, Etheridge, jun., p. 29. 
1910. — Producius semireticulatus Martin, Glauert, p. 87. 
1924. — Prodnetus .^emireticulaius Martin, Chapman, p. 36, sx)ecimens Nos. 
2746, 2748. 
1931.- — Productv.‘^ semireticulaf-us Martin, Hosking, pjn 8, 22. 
Types. 
Ryntypes. — G.S.W.A. 1/4967 (b), i/j mile west of Callytharra Spring, Woora- 
mel River District ; Callytharra Limestone. 
Paratypes. — G.S.W.A. 1/4967 (a), same locality and horizon. 
Other specimens. — IT. W.A. 12400, Fossil Cliff, Irwin River; Fossil Cliff 
horizon. 
G.S.W.A. 1/4668, south bank of Wooraniel River, mile above Callytharra 
Spring; Callytharra Limestone. 
G.S.W.A. 1/4654. 
Aus. Mus. F 36507, 36508, Barragooda Pool, Arthur River, North-West 
Division. Callytharra Stage. 
Aus. Mus. F 36237, Jimba Jimha Station, left bank of Gascoyne River, 
near Winnemia, North-West Division. Byro Stage. 
Aus. Mus. F 38147, 1% miles west of Williambury-Middalya Gate, Middalya 
Station. Callytharra Stage. 
