270 
but tbe latter is but indistinctly outlined. It is possible that a re-examination of this 
species, with the light thrown by D. illawarensis, may show a closer relation between 
the two. 
JLoc. and Horizon. Eichards’ Homestead, three miles south-west of Mount Britton 
Township (H. Hull ) — Middle or Marine Series, Bowen Eiver Coal Field. 
Gemis—PTEBLNOPEOTEH, Hall, 1884. 
Pterinopeeten, Hall, Pal. N. York, 1884, v., Pfc. i.. No. 1, p. xii. 
,, 33th Arm. Report, Regents Univ. .State Cab. N. York, 1884, p. 4006. 
Gen. Char. General characters of A.viculopecten, but the hinge-line long. Ears 
not well defined, being simple expansions or extensions of the upper lateral margins to 
the binge-line. Test ornamented with rays. (Hall.) 
Obs. Broi. Hall is, I believe, quite correct in separating from Aviculopecien 
those forms in which the ears are ill-defined, and not cut off from the body of the 
shell, esjiecially the anterior one, except in one valve, as is usually the case in the typical 
species of that genus. This is accompanied by a posterior obliquity of the shell, which 
is equally characteristic. I have not Sowerby’s “ Mineral Conchology ” to refer to, but if 
memory does not deceive me, Pecten papymceus, Sby., of the English Coal Measures, 
will fall into this genus. Perhaps also .Aviculopecten nodulosus, De Koninck,* will form 
another species. 
PrisBiNOrECTEN Detisii, sp. nov., PI. 40, fig. 9. 
Sp. O/iar. Shell of medium size, obliquely rhomboidal, the length and height 
being nearly equal, but the greatest length a little below the middle. Anterior 
and ventral margins regularly rounded, but the posterior margin sigmoidally curved. 
Hinge-line straight, a little shorter than the length of the shell. TJmbonal region 
more or less flattened ; beaks inconspicuous, anterior. Anterior ears small, triangular, 
separated by an undefined sulcus ; posterior ears flattened, margins concave, and their 
extremities pointed. Surface of the left valve with moderately strong, direct, and non- 
flexuous radiating cosfse, becoming much finer on the posterior ears, those on the 
body of the shell, at least, bifurcating, perhaps all ; concentric lines of growth wide 
apart. 
Obs. There is a strong resemblance between all the species of this genus, and it 
is at times difficult to differentiate between them. The present species is, however, a 
marked one, from the relative resemblance between the height and length. In general 
outline P. Eemsii approaches very closely the British Coal Measures species, P. papy- 
raceus, Sby., sp., but is more coarsely ribbed. In outline there is a marked correspondence 
with P, Iwosaeensis, Wiillcottjf but a similar difference exists here, in addition to the 
fact that the ribs are less numerous. In the extensive he'ght of its valves, our species 
is also very like P. ereclus. Hall, of the Chemung Group of North America. 
It is named in honour of Mr. C. W. De Vis, M.A., Curator of the Queensland 
Museum, to whom I am indebted for numerous contributions of specimens for the 
illustration of the present "Work. 
Another specimen, from the same Collection, with the nmbones and hinge-line 
wanting, closely resembles the type specimen in general appearance, but the radiiating 
costse are much finer, and far more numerous. They are also nodulated, but whether 
*I'aune Oalc. Carb. Belg., 188.3, Pt. 5, t. 37, f. 0. 
t Mon. U. S. Geol. Survey (Pal. Eureka District), 1884, viii., p. 232, t. 8, f. 9. 
