OOLITIC BIVALVES. 
97 
and figure agree in giving little importance to the posterior 
carina, so conspicuous here; and our species besides shows 
two ridges behind the carina. 
NUCULA-ty. 
Plate 23, fig. 8. 
A less convex species decidedly, but very much of the 
type of iV. variabilis.y Quenst., from the Lower Lias of 
Britain. 
MACTROMYA or COR BA? 
Plate 23, fig. 7. 
Very imperfect and not worth a figure. We have two 
specimens. 
CARDIUM TRUNCATUM -Sow. 
Mineral Concli., pi. 553, fig. 3. 
Occurs on the same slab as the Pecten above noticed, p. 86. 
The specimens are imperfect, but still recognizable. Mr. 
Etheridge identified it directly. 
ASTARTE or MYACITES ? 
Plate 23, fig. 10. 
With so many genera to choose out of, from Oolitic rocks, 
it is impossible to say of what genus this shell may be. 
It might be a Tancredia, a Corbicella, a Cajjsa ? or a 
Myacites —or it may even be an Astarte of unusual type. 
ASTARTE UNILATERALIS- —So w. 
Plate 23, fig. 10. 
Soiverby in Geol. Tr., 2nd Ser., vol. v., pi. 21, f. 14. 
The lateral beaks and regular concentric ridges find their 
parallel in A. lurlda , Sow., an Oolite shell which has a wide 
VOL. II. 
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