i8 
( aso 8. An attempt has been made in this case to illustrate 
some of the facts of evolution, such as distribution in time and 
space, the evolution and extinction of species and the adaptation 
of species to their environment. 
Case {>.— At the west end of this case is placed the small 
collection of Brachiopoda. These are not, in reality, Mollusca, 
but have hitherto usually been associated with them, and are 
placed here for convenience. In this case are also found the Pan- 
dorida, Telltmdw, the Teredinidce (shipworms, piddocks, etc.). 
Case lO.— Teredinidce, continued ; Pholadida, Myidce ; So- 
lenidee (razor-shells). 
Case 11. Psammobiidce ; Donacidce (wedge-shells); Ven- 
endcCy a very large family, which contains many beautiful shells. 
Case 12. — Veneridce, continued; Cham idee. 
Case 13. Cardidce (cockle-shells); Tridacnidce (giant 
clams). Two very large examples of this family may be seen in 
Hall 25. Cardidce . 
Case 14 .— Unionidce (river-mussels). These mollusks live in 
the ponds and streams of all regions of the world, except the 
coldest. They abound in individuals and species in our own 
region. - ^ 
Case 15.— Unionidce, continued; Arcidce (ark-shells). 
Case 16.— Mytilidce (mussels). A viculidce (wing-shells). 
This family, includes, among other species, -the " pearl oysters,” 
of which specimens are here shown. Other examples, some beau- 
tifully etched may be seen in Hall 32. Other remarkable genera 
are Malleus and Vulsella. 
Case 17. Aviculidce, continued; Pectinidce (scallop-shells); 
Spondylidce (thorny oysters). The last two families contain many 
shells which are interesting on account of their forms and their 
brilliant colors. 
Case 18 is on the south side of the court at’ the west end. 
In it are continued the Spondylidce ; Ostreidce (oysters); Dentaliidce 
(tooth-shells); Chitonidce. The latter is a remarkable family and 
contains over 300 species. The most striking characteristic of these 
animals is the serial arrangement of eight pieces of shell along- 
the back. 
Case 19 — Patellidoe (limpet-shells) ; Fissurellidce (key-hole 
limpets); Haliotidce (ear-shells). 
