267 
diagnosis * : — “ Shell inequilateral or oblique, slightly convex near the umhonal region 
or beak ; the ribs are also irregular and 'vavy, about thirty-live in number, and all meet 
near the umbo ; lines of growth obscurely wrinkled ; ears small, radiated, and coarsely 
Wrinkled. Prof. Morris does not state the dimensions of his shell ; proportionately our 
single specimen agrees with his, but apparently is individually larger.” 
The general obliquity of the valve, and the convexity in the umbonal region, 
certainly point to this species, but the anterior ear, well relieved from the body of the 
shell, does not accord at all with Morris’s figure, nor is there any indication of this in 
De Koninck’s illustration. I must confess to never having seen a complete individual 
of this species, and I am therefore rather in the dark as to its true appearance ; but 
the obliquity, and the great inequality of the valves, as expressed above, are certainly 
important characters. 
I now figure a rather similar Avioidopeolen (PI. 14, fig. 1) from Gympie, in which 
the anterior ear is similar in shape to that of Mr. Etheridge’s figure, but is less detached 
from the shell. This, for the present, must be regarded as referable to A. limmforniis. 
It is so rare to obtain any of these Australian Avimlopectens with the true shell 
remaining that identification in such a case, especially with mutilated examples, becomes 
difilcult. Such a specie on has been obtained in the Tatton Gold Eield, but space does 
not ])crmit of our figuring it. The valves are in apposition, and portions of the ears 
wanting. The larger valve is oval and decidedly convex, the smaller convex in the 
visceral region, but gradually becoming flat, or even concave towards the front margin, 
and to some extent also, the aides. In these we trace decided A. limasformu characters. 
Both valves possess about twenty-four broad, rather flattened riba, those of the one 
valve fitting into those of the other at the ventral margin, and causing the latter to 
become fluctuating. Corresponding interspaces exist crossed by very close projecting 
frills. One end of the shell (it is difficult to say which, the ears being removed) is convex 
in the larger valve, but sublobate in the flat or concave piece, another character of 
A. limeeformis. 
Until the entire appearance of the last-named is more familiar, the identity of 
these species must remain open, but if not A. limeeformis, it is possible that the present 
form, and Mr. Etheridge’s figured specimen, may form a separate species, as they appear 
to have several points in common. 
hoc. and Horizon. Coral Creek, Bowen Hiver, below Sonoma Road-crossing 
{R. L. Jack) — Middle or Marine Series, Bowen River Coal Field ; ? Gympie (JR.L. Jack) 
Gympie Beds ; ? Tatton Gold Field {R. L. Jack) — Gympie Beds, 
Aviculopecten ? imbbicaths, Etheridge. 
■^meulopcctcn ? mibrusatus, Etheridge, Quart. Journ. Geol. Soc., 1872, xxviii., Pt. 3, p. 326, t. 14, f. 2. 
,, ,, Etheridge fil.. Cat. Australian Foss., 1878, p. 6. 
Sp. Char. Shell inequilateral, and possessing twenty-two ribs, the ends or 
extremities of which imbricate or overlap in the cast ; there appears to be, or to have been, 
3- space between the end of each rib at its extremity, or along the ventral margin ; 
faint longitudinal markings run down each of the ribs, following their course. 
^Rtheridge.) 
Obs. An impression only occurs, and that of the inner sin'face, of one valve 
'^f this singular and doubtful shell. Our figure is taken from a gutta-percha cast of 
ffie impression left. That it belongs to the Asiphonida I do not doubt, and, I believe, 
* Quart. Journ. Geol. Soe., 1872, xxviii., p. 326, t. 14, f. 1. I am much puzzled by the central oval 
Joapressioii on the umbonal region. It cannot be a cartilage pit of the hinge, as it is in the wrong position 
°r such a structure. (JJ. E.,jun.) 
