4 
N. W. ARCHBOLD 
Measurements. In mm, e = estimate. 
Specimen 
Maximum 
width 
Ventral 
height 
Dorsal 
height 
Hinge 
width 
CPC 28026 
12.6 
_ 
7.9 
_ 
CPC 28028 
10.8 
— 
6.9 
9.4 
CPC 28029 
12.8 
— 
8.8 
11.2e 
CPC 28030 
11. Oe 
8.5 
— 
— 
CPC 28031 
14.0e 
9.4 
— 
12.Oe 
CPC 28032 
11.6e 
8.8 
— 
11.6e 
CPC 28033 
11.5e 
— 
— 
11.Oe 
Diagnosis. Medium sized Tornquistia with 
subquadrate shells at maturity. Maximum width 
often greater than hinge width at maturity. Dor¬ 
sal septa weakly developed including centrally 
developed median septum. 
Description. Ventral valve of pronounced con¬ 
vexity with distinctly inflated mesial portion of 
valve. Dorsal valve concave with demarcated 
deeper central region. Greatest width of shell 
anterior of hinge line at about one-third to one- 
half shell length. Exterior of shell smooth with 
faint growth lines. Interareas low, cardinal 
spines apparently short. Ventral umbo low. 
Ventral interior with blunt, relatively large 
teeth. Delthyrium distinct with pronounced 
thickening of shell beneath it. Minute pseudo- 
deltidium in apex of delthyrium. Median 
septum sharp posteriorly, extending weakly 
anteriorly for about one-half of valve length. 
Muscle scars usually weakly impressed. Valve 
floor, except for smooth muscle scars, marked by 
weakly developed radial rows of pustules. 
Weakly impressed parallel vascular trunks form 
low ridges adjacent to median septum. 
Cardinal process poorly known. Socket plates 
short but distinct. Lateral and accessory septa 
relatively weakly developed and separated by 
several rows of radial pustules which continue to 
anterior of valve. Short median septum devel¬ 
oped in valve centre with radial row of pustules 
anteriorly. 
Discussion. Tornquistia subquadratus is dis¬ 
tinguished from other Western Australian Per¬ 
mian members of the genus by its more sub¬ 
quadrate outline with a maximum width 
anterior of the hinge line. T. gregoryi Arch bold, 
1981 from the Late Artinskian Wandagee For¬ 
mation rarely exhibits a subquadrate outline but 
that species is distinguished from T. sub¬ 
quadratus by its incipient ventral fold. T. occi¬ 
dentals Archbold, 1980 from the Sterlitama- 
kian Callytharra Formation of the Carnarvon 
Basin is smaller and has a more trigonal shell but 
its internal structures appear similar to those of 
T. subquadratus. 
Tornquistia gibbera Afanas’yeva, 1977 from 
the Late Carboniferous Paren Horizon of the 
Kolyma-Omolon Massif is slightly less sub¬ 
quadrate than T. subquadratus and possesses 
less well defined rows of dorsal internal radial 
papillae. The younger T. troplcalis Grant, 1976 
from the Late Artinskian of Thailand is a tri¬ 
angular species unlikely to be confused with the 
new species, and is stated to have a short dorsal 
median septum. The Sakmarian Tornquistia sp. 
(Bamber & Waterhouse 1971, pi. 15, figs 16,17) 
from northern Yukon Territory', Canada, is 
larger than T. subquadratus and possesses liner 
rows of dorsal interior radial papillae. 
Suborder Strophalosiidina Waterhouse, 
1975 
Superfamily Strophalosiacea Schuchert, 
1913 
Family Strophalosiidae Schuchert, 1913 
Subfamily Strophalosiinae Schuchert, 1913 
Genus Strophalosia King, 1844 
Type species. Strophalosia gerardi King, 1846 
Discussion. The morphology, type species and 
palaeogeographical distribution of the genus 
were reviewed by Archbold (1986). 
Strophalosia invinensis Coleman, 1957 
Fig. 2A-E 
Strophalosia cf. invinensis. —Dickins 1976: 99. 
Strophalosia invinensis. —Archbold 1986: 99-102, 
figs 1A-Z, 4A-I (with synonymy). 
Material. Three internal moulds of ventral valves 
(CPC 24429-24430, CPC 28035) from locality TK5A, 
Scott Bluff, collected by W. J. Koop. 
Comments. Two of these specimens were fig¬ 
ured by me previously (Archbold 1986. fig. 
1 Y,Z) but they are refigured herein in magnified 
format to show the internal valve details includ¬ 
ing the muscle scars. The size and outline of the 
specimens and the nature of the muscle scars 
leave little doubt as to the assignment of the 
specimens to Coleman’s species, despite the 
absence of dorsal valve details. S. invinensis is 
well known from Sterlitamakian units in the 
Perth and Carnarvon Basins (Archbold 1986). 
