PLATE LI. 



FIG. 



1. MucRONELLA Peachii, vai. a (labiosa), p. 361. 



2. , var. ^ (octodentata), p. 361. 



3-6. MucRONELLA VARIOLOSA, p. 366; vars. 



7. ^ showing the growth of the superficial 



crust. 



8. MucRONELLA LAQUEATA, p. 368. 



