54 
K. L. Prexdergast. 
closely adpressed muscular apophyses supported in front by a pair of very 
short diverging ridges separated by a depression.” This clear definition is. 
somewhat marred, hoAvever, by their statement (p. 192) that “as now con- 
ceived the genus {Productella) is undoubtedly a “Dump-box” for primitive 
Productoids and includes the ancestral radicles of several later genera.'^ 
Which of these radicles, then, have they selected to typify the genus*? In 
view of Kozlowski’s Avork (1914) on the cardinal processes of Froduetus 
species this is a serious omission, as he has shown quite conclusively that not 
only does the cardinal process vary from species to species within a genus, 
but also Avith age among the members of any one species. On the other hand,. 
Dunbar and Condra may consider that all the species of Froductella, 
Avitli its present “dump box” composition, have a primitive type of cardinal 
process AA’hich therefore may be taken as characterising the genus; in other 
Avords, that Devonian Productoids of AAfiiichever “ancestral radicle” have 
the same type of cardinal process. And, significant in this issue, the only 
members of Leptalosia aaIioso cardinal i>rocesses are mentioned in the descrip- 
tion of the species are L. truncata and L. radicans, Devonian forms. It is 
just possible then that Dunbar and Condra have generalised about the 
Carboniferous forms from Avork on Devonian species. We do not knoAV 
AA’hether the cardinal jArocesses of the American Carboniferous Leptalosias 
are of the same primith^e pattern and cannot, therefore, yet separate them 
from the Scottish Carboniferous sub-genus Etlieridgina. 
One other ]Aoint AAliich might be produced in support of the separate 
existence of Leptalosia is the ])resence of teeth in the species of this genus, 
Oehlert having defined Etlieridgina as “Avithout cardinal teeth.” The mistake 
in this case is Oehlert^s, one of the co-types of E. complectens having at least 
the rudiments (or A’estiges) of teeth, a condition also found among the 
Carboniferous forms' of Lejjtalosia. In the face of this evidence I cannot 
regard Leptalosia as other than a synonym of Etlieridgina, 
Etheridgina muirwoodae n. sp. 
PI. vi, figs. 14, 1 5. 
1914. — Si1ro])}ialosia ,«p. Dth. fib. p. 34, pi. v, figs. 16-18. 
1918 . — ‘ ^ Strophalos'ia complecfc .s” ’ Eth. fib, p. 253, pb xl, figs. 11, 12. 
Syntypes. — Aus. Miis. F 16699, three specimens; Iaa'O are pedicle valves^ 
one sliOAA's two conjoined A'ah'es, figured by Etheridge as Strophalosia coynplect€7is 
(pb 40, fig. 12). Balmaningarra, Mt. iMarmion, Kimberley Dufision. Horizon not 
knoAvn. 
Topotype. — Aus. Mus. F 16812, one pedicle valve, figured by Etheridge as 
Strop]iaJos:ia complrcl ens (pb 40, fig. 11). Balmaningarra, Mt. Marmion. Kim- 
lAorley Division. Horizon unknoAvn. 
Other Material. — G.S.W.A. 10930, Mt. Marmion, Kimberley DiAusion. Hori- 
zon not knoAvn. (bS.W.A. 10929, north of Barrabiddy, Xortli-West Division. Hori- 
zon not knoAvn. Aus. Mus. F 3'S49S, 38499, Wandagee Station, Minilya KiA’er, 
Xorth-Wc.st Division. Wandagee stage. 
Diagnosis. — Shell small, transA'ersely oval to subquadrangular in outline,, 
adherent by body of pedicle valve and radiating marginal sjAines. Hinge- 
line less than greatest Avidth of shell, Avirh rounded alar angles. 
Pedicle A’alve Avith upturned lateral and anterior margins, visceral region 
adherent, flat. Hinge area Avide and fiat, psendo-deltidium large and tri- 
angular, teeth strong, divergent. Strong, long, adherent spines arising from 
caiMinal margin. Muscle impressions raised. 
