10 
LocalUics and Horizon. — ^llutlierford’s Quarry, near l’\uiey; I’avens- 
field (J. If'aterhonse). — Permo-Carboniferous — Lower Marine Series. 
Miiiino^ and Geological INEuseuin, Australian Museum. 
AviClLOPECTEN rONBEKOSUS, Sf. nov. 
(Plate V ; PI. XII, Fig. 4.) 
Specific Characters. — Shell very large, longitudinally orbicular, heavy, 
equilateral (when devoid of the auricles) ; dorsal margin long, nearly equal 
to the width of the shell. Convex valve (only one known) highly convex; 
uml)o large, })romiuent ; anterior and posterior slopes highly inclined ; 
anterior auricle very large, deeq)ly triangular, Avith a Avide open cmargination 
heloAV ; posterior auricle much smaller than the anterior (imperfect in all our 
specimens). Costte angular and coarse, Avith interpolated secondary ribs — Iavo 
between each pair of primaries. The anterior auricle hears numerous radiating 
riblets, crossed by equally plentiful transverse, curved lines, Avhieh probably 
extended over tlu' aa hole valve, producing a suh-dccussated pattern. Hinge- 
plate thick, grooved. 
Observations. — This is a large and ponderous shell, but the state of preser- 
A'ation does not permit us to give as extended a descrij)tion as we could Avish. 
Two examples attain the folloAviug dimensions — (a) seven and a half inches 
long by seven inches Avide ; {b) six and three-quarter inches long by six inches 
Avidc. On the surface of the valve distinct groAvth lines are not present, 
hut as these are presenTd on the large anterior auricle of at least one 
specimen, it is presumed they crossed the valve also. 
AVe possess no evidence of the presence of a chondrophore on the 
hinge-plate, so include the species in the genus Ariculopecfen provisionally, 
of Avhich it probably forms one of the largest species knoAvn. Tutting aside 
the question of a ehondrojdiore, on comparing A. ponderosm Avith Doltopecten 
Umoiformls, iMorris, Ave notice the absence of the obliquity of the latter, the 
heavier and more robust haljit, and the total Avant of any trace of the 
depression or groove extending obliquely from the umbo. To our minds this 
form is absolutely distinct from any other Ap^tralian Paheopecten. 
