2c, 





2d, 





2e, 



2/, 



2g, 



U 



TAB. II. 



Fig.' la, Balanus Hameri, lateral compartment, viewed externally. 



15, ,, „ carino-lateral compartment, viewed internally. 



Fig. 2a, Balanus bisulcatus, shell, 1\ nat. size. 



25, ,, „ rostrum, viewed externally, to show the commencement of 



the folding of the walls, l^ nat. size. 

 ,, var. plicatus, thrice nat. size. 



,, very young shell, probably belonging to this species, enlarged 



about seven times. 

 ,, scutum and tergum, external views. 



„ „ ,, internal views. 



Fig. 3a, Balanus dolosus, rostrum, much enlarged, viewed internally. 

 35, „ „ portion of basal plate, much enlarged. 



3c, 3d, „ ,, scutum and tergum, external views. 



Fig. 4<2, Balanus unguiformis, shell, twice nat. size. 



46, ,, „ shell, var. erisma, twice nat. size. 



4c, 4<d, „ „ scutum and tergum, external views. 



4c, 4/, „ „ „ „ internal views. 



Fig. oa, Balanus inclusus, shell, nearly thrice nat. size. 



55, „ „ basis of ditto, showing basal edges of the compartments. 



5c, „ ,, var., with its rostro-carinal axis elongated. 



r od, „ „ var., „ „ „ showing the narrow 



furrowed basis and lower portions of the six compartments. 

 oe, „ „ var. intermediate between the last two varieties, basal view of, 



nearly twice nat. size. 

 5/, off, „ „ scutum and tergum, internal views from a very young 



specimen. 

 Fig. 6a, Acasta undulata, rostrum viewed externally ; spinose var. ; twice nat. size. 

 65, „ „ lateral compartment, smooth var., twice nat. size. 



6c, „ „ basal cup. 



6d, „ „ scutum viewed internally. 



6c, 6/„ „ „ and tergum viewed externally. 



Fig. la, Pyrgoma Anglicum, shell, viewed from above, four times nat. size. 

 lb, „ „ scutum, internal view. 



7c, „ „ tergum, internal view, engraved from recent specimen, this 



valve not having been found fossil. 



