PERMO-CARBONIFEROUS PELECYPODA — ETHERIDGE . 179 
in question to either Gardinia , Ortlionota , or Pleurophorus appears 
to be impossible. It is a remarkable fact that the authors who 
have dealt with these shells invariably describe the cardinal 
margins as linear, narrow and concave. Indeed the remarks 
of both Dana and Morris indicate their mental uncertainty as to 
what genus they should be referred to. 
I therefore propose, under the circumstances, the genus Stutch- 
buria for the reception of Ortlionota ? costata , Morris, and if 
differing from it 0 . ? compressa also, in honour of Samuel Stutch- 
bury, the pioneer Naturalist, and one of the two pioneer Geologists 
of Australia. 
The characters of the new genus will be as follows : — 
Shell transversely elongate, equivalve, very inequilateral, the 
posterior end the longer, more or less compressed, closed, test 
thin ; posterior slopes always rounded ; a mesial sulcus sometimes 
present in each valve ; edentulous ; ligament supported on the 
thickened hinge plates ; dorsal or cardinal margins erect and 
sharp ; um bones very anterior ; the anterior adductors large, 
with single smaller supplementary scars (l) between them and the 
umbones, in the cavity of which there are at times other scars ; 
posterior adductor scars large, but less defined ; pallial lines 
simple ; sculpture concentric and at times radiate. 
The form, edentulous nature of the thin shell, internal ligament, 
and often radiate sculpture indicate the Solemyidse as the family 
to which Stutchburia should be referred. The representatives of 
this family are Solemya , Janeia , and Clinopistha , to which Mr. 
W. H. Dali has suggested* the addition of Orthodesma and 
Whitevesia . Now, the proposed new genus, although resembling 
Solemya in its edentulous nature, and simple pallial line, differs 
entirely in having the ligament practically posterior, and no trace 
of the umbonal ligamental clefts. From Janeia it is easily distin- 
guished by the equality of its valves, and from Clinopistha by out- 
line, the presence of an internal ligament, and by the fact that the 
umbones are anterior and not posterior. The reference of Ortho- 
desma , as described by Hall and Whitfield, to the Solemyidse does 
not appear to be well established, but two of the species so 
described by Ulrich, from the Lower Silurian of Minnesota 
approach much nearer to Stutchburia , especially in their muscular 
scars. 
With regard to Whitevesia , the edentulous nature of the hinge, 
simple pallial line, and internal ligament, indicate a departure 
towards our shell, but the grooved hinge plate, and both external 
and internal ligament if present, but of which there seems to be 
some doubt, as well as the very much feebler muscular scars, 
* Dali — Trans. Wagner Free Inst., iii., 1895, p. 515. 
