Permian Productinae and Strophalosiinae of W.A. 
11 
Aulosteges Hclmersen is distinct from Strophalosia in the possession of 
dendritic muscle impressions. The pedicle valve carries an area, usually 
high, while that of the brachial valve is small or absent. The articulation is 
weak, the pedicle valve being without teeth. 
It is obvious, then, that within his sub-family Strophalosiinae Schuchert 
has included forms very different in structure. Its attached habit seems an 
insufficient reason for the separation of Chonopectus from those forms, the 
Chonetinaej to which it is closely related, and Schmidt's placement of it 
(1929, p. 21) in that sub-family must be regarded as the more correct. 
Aulosteges^ both in the possession of dendritic muscle impressions and in 
the pattern of the brachial impressions, approaches more closely to the 
Productinae than to Strophalosia and its replacement in the Strophalosiinae 
would seem a more natural position. 
It is admitted, however, that little is known of the derivation of 
Aulosteges and Strophalosia, Licharew (1934 (a), p. 509) has, on the 
ground of insufficient evidence for their separation, abolished the sub-families 
and included all the genera in Prodiictidae. He reverts to King's diagnosis 
and defines the family as 
^‘Shells free, attached by spines or cemented directly. Dorsal valve 
flat or concave. Cardinal margin straight. The whole surface or only 
the shoulders of the ventral valve bedecked with hollow spines. Cardinal 
process prominent. Dorsal valve with reniform brachial impressions." 
To Productus sensu lato, Chonetes sensu lato, Strophalosia^ Productellay 
Aulosteges and Etheridgina he adds Teguliferina and Scacchinella. Dunbar 
and Condra (1932, pp. 189, 191) and Diener (1927, pp. 30 and 31) also in- 
cluded these genera in the Producitidae. 
Scacchinella Gemmellaro and Teguliferina Schellwien are the genera 
intermediate in character betiveen Aulosteges and Productus respectively and 
the Richthofeniidae. These genera, however, possess characters which would 
ally them to the Richthofeniidae rather than to the Productidae. Scacchinella 
and Aulosteges possess in common the high produced area (higher and more 
produced in Scacchinella) and the method of attachment by the tip of the 
area. Scacchinella is quite distinct, though, in the possession of a well- 
developed median septum in the pedicle valve and in the character of the 
cardinal process with its supporting rods. In these characters it approaches 
Richthofenia, Teguliferina in which the productoid characters are still 
recognisable, resembles closely the Richthof eyiiidae in its mode of growth and 
in the operculiform character of the brachial valve. It seems reasonable tO' 
assume that the peculiar characters of Richthofenia are in part a result of 
its mode of growth and therefore that Scacchinella and Teguliferina^ as the 
possible forerunners of a group so distinctive as the Richthofeniidae, should 
be included in that family. 
A different method of approach to this subject of the classification of 
the Productidae has been used by Sutton (1938), with astounding results. 
As he points out, the shape of the visceral cavity as a diagnostic feature 
has been given prominence in Productid literature although no author has 
attempted a classification based upon that feature. Sutton has. He divides 
the Mississippian Productidae into two sub-families, the ProductelUnae and 
the Productinae. The ProductelUnae have a thin visceral cavity of the type 
described by Fredericks as Productus typici and include the genera 
