PLATE XII. 
J. Navicuna centitis, Donkin. S.V. 
~ 
Navicuxa acrosPH#Ri4, De Brébisson. 
. Navicuza e1BBa, Ehrenberg. S. V., a large speci- 
men from Loch-Oich deposit; it is frequently 
smaller and more dilated at the extremities than 
in the figure. 
4. Navicuta TaBeLzaria, Ehrenberg. 8. V. 
5. Navicua scoruLorum, De Brébisson. 8.V. The 
“ 
striz are much finer than delineated in the 
figure. 
NavictLa Limosa, Kiitzing. @, var., with rounded 
extremities; 5, 8S. V., typical form. 
. Navicuna ventRIcosA, Ehrenberg. This species is 
generally more tumid in the middle than in the 
specimen figured. 
