BIVALVIA. 33 
Pecten Rusnpenensis, Lyc. Tab. XXXTII, figs. 4, 4a, 44, 4. 
Testa aquivalvi, suborbiculart, acuta, auriculis inequalibus (auricula antica majora), 
valvis plano-convexis rugis concentricis elevatis, crebris, inferne squamatis, squamis brevibus, 
regularibus delicatissime instructis. 
Shell equivalve, suborbicular, acute, moderately convex ; auricles unequal (the anterior 
one being the larger) ; the valves have a few plications of growth, and very densely arranged, 
elevated, concentric rugee, which are slightly wrmkled towards the apices, but towards the 
middle of the valves become short, regular, scabrous elevations, disposed checker-wise with 
those above and beneath, so that when viewed obliquely the ornamentation resembles 
that of an engine-turned watch; this is more especially the case with the surface of the 
right valve, which has the concentric rugze more delicate and closely arranged, and also 
the scabrous elevations ; in other respects the valves are alike in the design of their 
ornamentation. 
A beautiful suborbicular species ; the minute scabrous elevations arrest the finger when 
it is passed upwards over the surface. It is very rare. 
Geological Position and Locality. The Cornbrash of Rushden, Northamptonshire, in 
the collection of the Rev. A. W. Griesbach. 
Pecten Worastonensis, Zyc. Tab. XX XIII, figs. 2, 2a, 24, 2c. 
Testa ovato-orbiculari compressa, equivalvi, aurieulis inequalibus transverse plicatis et 
radiatim costatis ; valva dextra concentrice striata et radiatim costata ; striis tenuissimis, 
inferne lamelloso-rugosis ; costis inequalibus nodosis ; numerosis, inferne evanescentibus ; 
valva sinistra striis subtillissimis concentricis regularibus. 
Shell ovately orbicular, slightly convex, equivalve, with unequal auricles, the anterior 
one being the larger ; they have numerous transverse plications and two or three radiating 
costz ; the surface of the right valve has concentric striations and radiating coste ; the 
striations are very fine and irregular ; the middle and lower portion of the valve is occupied 
by irregular, scabrous, concentric plications ; the radiating coste are very numerous, 
irregular, and knotted ; they gradually disappear towards the middle of the valve. The 
left valve has very delicate, regular, concentric, densely arranged striations. 
This rare Pecten differs from Pecten Dyonisius, Buv., chiefly in bemg equivalve, and in 
the dissimilarity of the ornamentation in the opposite valves. 
Geological Position and Locality. The Great Oolite of Wollaston, Northamptonshire, 
in the cabinet of the Rev. A. W. Griesbach. 
OU 
