Permian Produotinae and Strophalosiinae op W.A. 
29 
Remarks. — From the Fossil Cliff Beds, Irwin River, are found shells 
which possess an elongated narrow area. Those specimens from the Byro 
sandstone of the Wooramel River have a distinct though not large area, while 
a specimen from the Kennedy sandstone (North-West Division) has been 
identified as Aidosteges ingens Hosking, although it differs from the Byro 
specimens only in the greater development of the area and the horizontality 
of the cardinal process. The stratigraphical relationships of these beds are 
given by Raggatt (1936) and Rudd and Dee (1932, MSS. unpublished). 
N.W. Division and 
W^ooramel River. Irwin River. 
Gascoyne Series 
5. Wandagee 
4. Kennedy 
3. Byro 
2. Wooramel 
1. Callytharra = Fossil Cliff Beds, 
The specimens of these species may, then, be arranged in a time series, 
in which the area increases in size as the fossil-bearing rock is 3 munger in 
age. The cardinal process also changes gradually through this series. In the 
typical Productus (e.g. Dictyoclostus semireticulatiis (Martin)) the cardinal 
process is erect and in specimens with small areas this statement also holds 
for Taeniothaerus subquadraius (Morris). In Aulosteges haracoodensis Eth. 
fll., however, as in all Aulosteges the cardinal process has become bent through 
a right angle. This change, from vertical to horizontal, takes place gradually 
and keeps pace with the growth of the cardinal area. The suggestion is there- 
fore made that Taeniothaerus suhquadratus (Morris) is a transitional form 
connecting an unknown Rroductus with Aidosteges haracoodensis Eth. fil. 
KEOTOVIA Fredericks. 
1928. — Fredericks, G., Bull. Com. Geol. St. Petersh., 46, 1927, p. 790. 
Genotype. — P. spindulosus J. Sowerhy, 1814, Min. Conch., Vol. 1, pi. Ixviii, 
fig. 3. 
Diagnosis . — Small thin-shelled product!. Pedicle valve convex, brachial 
valve concave to geniculate, closely following curve of pedicle valve. Orna- 
mentation of fine spines in irregular quincuncial arrangement covering whole 
shell surface; spine bases elongated in anterior part of shell. With or with- 
out weak concentric wrinkles, median sinus only slightly developed or absent. 
Internal structures unknown. 
Comparison ivith other genera. — This genus differs from Fustida Thomas 
in the absence of marked concentric wrinkles and in the nature of the visceral 
cavity. In Pustida the brachial valve is flatfish, forming a large visceral 
cavity, whereas in Krotovia the brachial valve follows the pedicle valve so 
closely that the visceral cavity is thin. Schuchert and Le Vene consider that 
this is not sufficient distinction as they say (1929, p. 72) of Krotovia “appears 
to equal Pustula Thomas.'^ The shape of the body cavity is, however, a 
feature of diagnostic importance, and I have, therefore, adopted Frederick’s 
genus. 
Frederick’s diagnosis of Krotovia (p. 790) states: “The shell has an 
oval configuration and a plain surface. The ornamentation consists of spines 
only,” and in the Russian text (p. 779) “Sometimes irregular ribs and folds 
