229 
however, is not entirely flat ; the result of this formation is that the heak of 
the right valve is thicker than the other. The heaks are placed near the 
middle of the hinge line. The ears are large, suhequal, and flat ; the anterior 
ear is better defined than the posterior, and is separated from the rest of the 
shell by a rather deep curved sinus. Its surface is ornamented with about 
twenty-five principal, rather thick, radiating folds having their origin at the 
heaks ; between these and at some distance from the heaks interpose other 
and thinner folds, which, in turn, increase before reaching the margins. It 
must he noted that this arrangement is not absolutely regular, that the 
principal folds are not always the same distance apart, and that the number 
of interposed folds is very variable. All these folds are crossed by concentric 
waves of growth. 
Dimensions. — The length is nine, breadth seven and a half, and 
thickness one and a half centimetres. 
Relations and Differences. — According to McCoy, who seems to 
have had the opportunity of examining tlie shell itself of this species while I 
have only had internal casts, it is somewhat like his A. quinquelineatus of 
Ireland ; it differs from it by its intermediate folds being thinner and their 
arrangement less definite near the margins, it is also more convex. 
Horizon and Localities. — It seems rare in a fine-grained sandstone 
at Harper’s Hill (McCoy). Mr. W. B. Clarke found it in a similar sandstone 
at Muree. 
Avictjlopecten LIM..EFOKMIS, J. Morris} 
PI. XXII, Pig. 4. 
Recten limceformis, .1. Morris, 1845, in Strzelecki’s Phys. Descr. N.S. Wales, 
and V. D. Land, p. 277, pi. 13, fig. 1. 
Aviculo'pecten ? limceformis, E. Etlieridge, 1872, Quart. Journ. Geol. Soc., XXVIII, p. 
326, pi. 14, fig. 1. 
This is a very large, inequivalved, inequilateral, transversely oval, and 
slightly oblique shell. The right or upper valve is much more convex than 
the lower. According to Mr. J. Morris the ears are relatively small. The 
surface is ornamented wdth thirty-five or thirty-six angular, radiating folds, 
simple or only rarely bifurcating, and consequently clearer at the margins 
* [Compare Waagen, Records Geol. Survey India, 1886, XIX, p. 27, t. 1, f. 8 ; Salt Range Fossils (Pal. 
Indica), 1891, IV, Ft. 2, p. 130,, t. 5, f . 8 ; R. Etheridge, Junr., Geol. and Pal. Q’land., 1892, p. 266, t. 14, f. 
1. — W.S.D.] 
