95 
CASE 12. — Turbinidae (Top Shells) ; Neritidae; Naticidae; 
XenophorMae. 
CASE 13. — Capulidae (Cup and Saucer Limpets) ; Ampul- 
lariidae (Apple' Snails) ; Littorinidae (Periwinkles). 
CASE 14. — Melanidae ; Turritellidae; Vernietidae (worm 
shells, the shells being more or less contorted like worm tubes) ; 
Cerithidae. 
CASE 15. — Stromhidae (Conch Shells) ; CypraeMsiC (Cowr- 
ies), a family containing some of the most beautiful shells 
known. 
CASE 16. — Doliidae (Tun Shells) ; Cassidae (Helmet 
Shells). 
CASE 17. — Tritonidae (Triton Shells). 
CASE 18. — Muricidae, a large family of miostly spiny and 
roughened shells. 
CASE 19. — Nassidae (Dog Whelks) \Bucinidae (Whelks) ; 
Turhinellidae. 
CASE 20. — Fasciolaridae; Mitridae (Mitre Shells) ; V olu- 
tidae, a family containing many large and beautifully-colored 
shells. 
CASE 21. — Marginellidae; Harpidae (Harp Shells) ; Olwi- 
dae (Olive Shells). 
CASE 22. — Conidae (Cones), an extensive family living 
mostly in warm seas. 
CASE 23. — Terehridae (Auger Shells). 
CASE 24. — Bullidae. 
CASE 25. — Materials illustrating , two groups of Mollusks, 
many of whose members have the shell rudimentary or wanting 
entirely. Many of these animals are represented here by beauti- 
fully-executed glass models ; Limnaeidae . 
CASE 26. — Limnaeidae continued; Stenogyridae, this fam'ly 
and the remaining ones, which belong to the order Pulnonata, 
are air-breathing Mollusks, the largest belonging to the genus 
Achatina. Most of the species live in Africa, where they remain 
in trees, descending to lay their eggs. Some of the eggs are 
exhibited. 
CASE 27. — Stenogyridae continued; Pupidae; Bulimdae; 
Helicidae 
CASES 28, 29, 30, and 31. — Helicidae (Air-breathers), 
a large family containing over 6,500 species. Many of the most 
