ON MOLLUSCA. 281 
9. An heterostomatous shell, lip subcontinuous and folded 
back. Gen. Pupa, Lam. 
10. A cricostomatous shell, lip continuous. Cyclostoma 
elegans. 
11. A tubular cricostomatous shell, fissure subspiral. S¢dc- 
quaria anguina ; Serpula anguina, Gm. 
12. A tubular shell, cricostomous and subspiral. Vermetus 
(Serpula) Adansonii. 
The figures of univalve non-spiral shells and opercula in- 
clude, 
1. A symmetrical tubular non-spiral shell. Dentaliwm 
entalis. 
2. A symmetrical shell, with the beak or apex posterior ; 
a. posterior—b. anterior. 
3. A symmetrical shell, with the beak or apex anterior. 
Patella cymbalaria, Lam. 
4, A non-symmetrical shell. Siphonaria radiata. 
5. A non-symmetrical shell, with the apex or beak posterior. 
Hipponiz. 
5, a. It’s foot. 
6. A subspiral shell with a perforated disk. Hadvotvs. 
The following are opercula: 
7. Multispiral operculum. Genus Trochus. 
8. Paucispiral op. Gen. Turbo. 
9. Unispiral op. Gen. Nerita. 
10. Subspiral op. Gen. Phasianella. 
11. Unguiculated op. Gen. Murex. 
12. Unispiral inarticulate op. Gen. Natica. 
13. Subunguiculated op. Gen. Purpura. 
14, Squamous op. Gen. Helicina. 
15. Lamellateous op. Gen. Buccinum. 
16. Radiated op. Gen. Navicella. 
