Permian Productinae and Strophalosiinae of W.A. 
53 
Description. — This genus was tirst described from the Carboniferous of 
.Scotland and is now also known from the American Carboniferous and the 
Permian of Australia. The shells are always small and vary in their mode 
of attachment with the nature of the foreign body which acts as host. Thus, 
in the Scottish Carboniferous forms, where they occur more usually on 
crinoids, the spines along the hinge-line are greatly elongated and embrace 
the stem which may grow over and completely enclose the brachiopod. In 
the American forms (and in the Australian) on the other hand, which attach 
themselves to a flat surface, the shell is cemented directly by the whole of the 
pedicle valve — the spines along the hinge-line being produced parallel to the 
.surface and adhering thereto. 
The area, in those forms in which it has been observed, is narrow and 
extends along the total length of the hinge-line. In the pedicle valve teeth 
may be present or as is more usual in the Scottish forms they are represented 
only by vestigial or rudimentary small lumps. 
Discussion. — In his original descri 2 :>tion of this genus Oehlert quotes the 
date as 1877 ; this was probably an error for 1887. In founding the genus, 
Oehlert referred it to ProductuSj it having, he thought, in common with that 
genus, the absence of area and of teeth and the j^edicle valve not distorted 
by cementation. 
The definition of the sub-family StrophaJosiinae by Schuchert (1913) 
as productids anchored by spines or by most part of the iicdicle valve, 
allowed Etheridgina, like Chonopectiis, to be included in the subfamily with- 
out inferring any relationship to Stroplialosia or indeed, any similarity other 
than that of habitat. Greger (1920, p. 535) referred a number of small 
adnate American species, formerly included in Stropiudosia, to this sub-genus 
hut acce])ted it as a sub-genus of Prodnc-tus. Careful examination of the 
type specimens of the genotype of this sub-genus shows, however, that ii 
should be referred to Stroplialosia rather than to Productus. Several of the 
co-types (Royal Scottish Museum, Nos. 5074-5083) show a small though rela- 
tively well-develo])ed area and teeth have also been seen on one specimen. 
Also the adductor scars of the brachial valve are non-dendritic. These 
features clearly distinguish it from Productus and show its relationshijt to 
Stroplialosia-. Etheridgina is, therefore, ])laced here as a sub-genus of 
Stroplialosia. 
In 1932 another productid sub-genus — Leptalosia — was ])ro|)osed by 
Dunbar and Condra (1932, 2 >p. 189, 190, 2(i0) to include adnate rroduclids 
attach(‘d by the wliole of the ])cdicle valve. The members of this sub-genus 
had an area and hinge teeth in the ]K'dicle valve of the older S 2 )ecies (the 
sub-genus ranged from Ujiper Devonian to CarI)oniferous) and a distinctive 
small jn'oductelliform cardinal ])rocess. The genoty]m is Etheridgina 
scintilla (Beecher) ((]uot(*d by them as Stroplialosia scintilla although this 
Species had been referred to Etheridgina by Greger in 1920). The sub-genus, 
according to its authors, differs from Etheridgina in ijossessing a cardinal 
area and in the foian of its cardinal ])rocess the resemblance of the two 
genera bdng liomoeomorphic and the result of a similar habit of growth. 
It is worth considering these diffei-ences further. As has been already 
mentioned, the type sy^ecies of Etheridgina does ptossess an area. Dunl)ar 
and Condra (o]>. cit., o. 2fi0) describe the 2 >roduetellifoj’m cardinal prnce-:^ 
:as ^‘very small and bifid, composed of two narrow posteriorly facing and 
