238 
Aviculopecten Illawaeensis, J. Morris} 
PL XXII, Pig. 1. 
Fecten lllciwcirensis, J. Morris, 1845, In Strzelecki’s Pliys. Descr. X. S. Wales and Y. D. 
Land, p. 277, pi. 14, fig. 3. 
,, ,, J. D. Dana, 1849, Gieol. Wilkes’ U.S. Explor. Esped., p. 705, pi. 9, 
fig. 9. 
This is a large, beautiful, oval, ineqiiivalved, sub- equilateral shell, 
broader than long, with rather large ears. There are from eighteen to twenty 
radiating folds on the surface ; these folds are rounded, smooth, and separated 
by furrows of about the same breadth. The right valve is more convex, and 
decidedly more regularly ventricose than the left, and its beak is more 
developed and recurved. One-third of the breadth of the left valve touching 
the ventral margin is depressed and nearly flat. 
Dimensions. — The length is eleven, breadth thirteen, and thickness 
6‘25 centimetres. 
Delations and Differences. -~1 know no Palaeozoic species of this size 
that could be confounded with it. It can easily be distinguished from the 
preceding by the simplicity of its radiating folds. 
Horizon and Localities . — Dana expresses a doubt as to the locality — 
Illawarra — given by Morris as the spot furnishing this Aviculopecten. Dana 
himself, and Mr. Clarke also, found it at Harper’s Hill. 
Genus — Aphanaia, L. G. de Koninch} 
This shell is inequivalved, inequilateral, gibbous, with a posterior 
obtuse wing, and an apparently edentulous, straight hinge. Its beaks are 
anterior and separated by a hollow area, and having also a ligament. The 
surface is marked with large concentric rings, usually very unequal, and like 
those of some species of Dioceramus, to which some Authors have assigned 
examples of Aphanaia. Their chief characteristic lies in the number and 
shape of their muscular impressions ; the impression of the adductors is 
double, very large, placed posteriorly, and very much nearer the ventral 
margin than the hinge line ; the diameter of one is nearly double that of the 
' [This has been made the type of a gemxs—Deltovecten — R. Etheridge, Jnnr., Geol. and Pal. Q’land, 1892, 
p. 269, t. 41, f. 3, t. 43, f. 2, W.S.D.] 
From a, privative and (pavalos, brilliant. 
