34 
K. L. Prexdergast. 
The dendritic muscde impressions are situated in sub-triangular depres- 
sions on each side of the median septum. At the base of each, the brachial 
impression arises, runs parallel to the hinge-line almost to the lateral margin,, 
then turns anteriorly to form an open loop. On no specimen have the im- 
pressions continued to the median septum. In the area circumscribed by the 
brachial impressions the inner shell surface is smooth and shiny, elsewhere 
it is finely iDitted. 
Figure 5. 
Cardinal Process of Aulosteges wangenheimi (Verneuil). Permian. Mt. 
Grebeni, near Orenburg, Russia. B.M. BB 3278. (a) vertical, (b) lateral 
(c) horizontal (X3). 
Coynimrison with other genera. — The genus Aulosteges is distinct from 
members of the Strophalosiinae in the possession of a high reclined area, 
poor articulation, a cardinal process orientated perpendicular to the commis- 
sural plane of the valves, the triangular extension of the cardinal margin of 
the brachial valve and the dendritic adductor impressions in the brachial 
valve. 
The high area of Aulosteges and the horizontal inclination of the cardinal 
process serve as distinguishing features from the Productus spinosi group. 
In view of the prevailing opinion of Russian palaeontologists that 
Aulosteges is a synonym of StropJialosia^ the differences between the two 
genera will be considered more fully. Netschajew (1911, p. 144) states that, 
the only significant feature distinguishing the two is the presence of deltidial 
spines in Aulosteges. Such a statement completely ignores the differences in 
the internal structure of the brachial valve. It must be admitted, however, 
that the internal features of the Russian species Strophalosia horrescens^ 
S. fragilis and 8 . gigas are very similar to those of Aulosteges. The muscle 
impressions are dendritic, the cardinal process inclined towards the horizontal 
and the pattern of the brachial impressions productoid. It is here that the 
error lies, for those species mentioned above do not belong to the genus 
Strophalosia^ they are Aulosteges, 
Licharew (1937, p. 128), while stressing the synonymity of Aulosteges 
and Strophalosia, recognised that the Russian “ Strophaloskd^ did not come 
within the accepted conception of that genus. He compromised by suggesting 
