135 
Case 5. — Marginellidce ; Vo lu tides ; a family containing 
many large and beautifully colored shells. A rare shell is Voluta 
Junonia. It formerly sold for as much as $200; now for $8 or $10. 
Case 6 . — Harpides (harp-shells); divides (olive-shells), 
great favorites with collectors; and Pleuo to nudes . 
Case 7 .'—Conides (cones), an extensive family, living mostly 
in warm seas. Few families make a handsomer collection than 
do the cones. Teribrides (augur-shells). 
Case 8 .— Materials illustrating two groups of mollusks, many 
of whose members have the shell rudimentary or wanting entirely. 
The Nucleob ranch ia ta are all pelagic animals, swimming at the 
surface of the sea. The Opisthobranchiata are also marine and 
are termed sea-slugs. Many of these animals are represented 
here by beautifully executed glass models. 
Case 9 .— A number of families of air-breathing mollusks 
(. Pulmonata), Stenogyndes. 
Case XO.—Stenogy rides, continued. The genus Achatina 
contains some of the largest known air-breathing shells. Most of 
the species live in Africa, where they remain in trees, descending 
to lay their eggs. Some of the eggs are exhibited. Pup ides ; 
Jim ti ft fP 
Cases 11, 12 and 13.— Representatives of the very ex- 
tensive family of Helicida. Over 6,500 species of this family 
have been described. All are air-breathers, inhabiting all coun- 
tries, except those very cold. Many of the most attractive species 
in these cases are from the Philippine Islands. Some species of 
Bulimus reach a length of six inches. They lay large eggs which 
resemble those of birds. Some of these are shown. 
Case 1 4. — Pteropoda , mollusks inhabiting the open sea. 
The shell is often absent; Lwiaeides (the slugs). 
Case 15.— The Cephalopoda , a class which includes the 
nautilus, the squids, the species of octopus and the argonauts. 
Specimens of a number of species in alcohol are in one of the 
wall-cases. Shells of the nautilus have been sectioned so as to 
show the internal structure. A considerable number of the soft 
cephalopoda are represented by means of glass models. A model 
of the giant squid of the coast of Newfoundland is suspended 
overhead. In Hall 24 is a model of the giant octopus of the Paci- 
fic coast of the United States. 
