17. Cerithium. (Buccinum Africanum, Lister.) 
h. The head. 
i... tentacula. 
m. « mouth. 
ee. .. eyes. 
T. .. trunk. 
Tb or ilin 
o. .. operculum. 
18. Limax phosphorescens, 1-2. 
19. 20. Yetus, Adans. (Buccinum Persicum, Lister.) 
h. The head. 
tt. .. tentacula. 
m. .. mouth. 
ee. «.. eyes. 
T. . trunk, 
k. .. extremity of the manitle, forming a sort of pipe. 
nn. membrane accompanying the mantle. 
ape A ace of its enormous foot. 
21. Halyotis. 
h. The head. 
wt. .. four tentacula. 
ee. .- eyes. 
n. _.. membrane which attaches the lower tentacula to the head. 
i, .. two anterior extremities of the mantle, coming out of the se- 
cond hole of the shell. 
