PLATE LI. 



FIG. 



1. MUCBONELLA PEACHII, Var. a (LABIOSA), p. 361. 



2. , var. /3 (OCTODENTATA), p. 361. 

 3-6. MUCRONELLA VARioLOSA, p. 366; vars. 



7. , showing the growth of the superficial 



crust. 



8. MUCRONELLA LAQUEATA, p. 368. 



