102 DEVONIAN FOSSILS 
Generic Position. This form is tentatively referred to Pro- 
leptostrophia (Caster, 1939), which has been defined in brief by 
Cooper (in Shimer and Shrock, 1944, p. 341) as ‘‘Smaller than 
Leptostrophia with nearly flat dorsal valve; ventral musculature 
like Leptostrophia; dorsal interior with small bilobed cardinal 
process and small posteriorly located adductor field." P. affinalata 
agrees with this diagnosis except for the two minute knobs outside 
the main prongs of the cardinal process, making it into a quadrifid 
one. However, P. affinalata closely approaches Leptostrophia, and 
without a bigger range of specimens one cannot be sure that fully 
mature forms are present. 
The holotype of the new species possesses a few weakly- 
developed discontinuous wrinkles, but these are not the “strong 
concentric wrinkles as in Leptaena” to which Caster refers as 
distinguishing Rhytistrophia. There seems to be a gradation from 
shells without wrinkles into the strongly wrinkled ones accom- 
modated in Rhytistrophia. 
Affinities. The trivial name of the new species is intended to 
indicate its affinity with P. alata (Chapman, 1903) from north of 
Lilydale (for precise locality see Gill, 1940), which is Upper 
Yeringian. The two species have a similar crenulation, standing 
in eontrast with another group of protoleptostrophids which has 
the whole height of the ventral interarea occupied by the teeth file 
as in the genotype of Leptostrophia. The two species also have 
similar alate eardinal angles, and both possess a quadrilobate 
eardinal process. However, P. affinalata differs from P. alata 
chiefly in the following points: 
(1) The ventral muscle field of the new species is much more 
developed than in the compared species. P. affinalata has a large 
exeavated muscle field with a long median septum, strong dental 
ridges, and ridges dividing the diductor muscles into bundles. P. 
alata has a smaller, unexcavated muscle field with but moderate 
dental ridges, and the diductor muscles not divided into bundles 
by ridges. 
(2) The interior of the ventral valve is much more strongly 
papillose in P. affinalata than in P. alata, and the latter is char- 
acterized by a row of larger papillae ranged along the dental 
ridges. The second feature is seen in a number of protolepto- 
strophids including P. plateia, and undescribed forms from Kil- 
lara and Heathcote districts in Victoria. No such row of papillae 
oceurs in P. affinalata. 
Distribution. Brachiopods not specifically separable from P. 
affinalata have been collected from Hull Road, Mooroolbark. 
