220 
are accidental, being produced by the form of the sub- 
stance or shell that the individuals were attached to when 
young. We have found it proper to refer all three to 
one species, and retained the name conica as being the 
best of the three. 
We have specimens from Folkstone, Parham Park, 
Chute Farm, Warminster, and Blackdown ; those from 
the latter place are selected for the present figures. 
The necessity of removing this fossil from the genus 
Chama has induced us to take it again under considera- 
tion. 
EXOGYRA laevigata. 
TAB. DCV.— /g.4. 
Spec. Char. Elongated, curved, smooth ; deep 
valve rather gibbose, obtusely keeled ; keel 
near the hollow side ; flat valve semicircular, 
pointed, its beak small. 
Nearly double the size of the last, also more elon- 
gated and curved with proportionally smaller beaks. 
The figures are from Irish specimens in a compact 
sandy limestone, from the Green-sand formation. We 
have seen English ones very similar. 
EXOGYRA undata. 
TAB. DC V.—figs. 5. 6. & 7. 
Spec. Char. Convex ; deep valve keeled along 
the middle, and marked with branching ridges 
that diverge from the keel; flat valve plain. 
A small and rare shell, found at Blackdown. Fig. 5. and 
6. represent specimens lent us by H. H. Goodhall, Esq. 
