236 TlMEHRI. 
they still bear the name of Zoophytes to denote the plant- 
like appearance. A very curious fa<5l in their history is that 
the rooted forms produce buds utterly unlike them- 
selves, which break off and swim about as jelly-fishes ; 
and these jelly-fishes produce eggs which hatch out, not 
into other jelly-fishes, but into hydra-like forms which 
become rooted and develop into plant-like colonies simi- 
lar to the original form and producing similar sets of 
buds. This series of changes shews an alternation of 
generations that is most peculiar. These animals belong 
to the class Hydrozoa^ already described. 
On this same table are seen large univalve helmet- 
shells (Cassis) used in making cameos, and small speci- 
mens of the double-valved clams. The giant clams 
(Tridacna) of the East Indies are often more than five hun- 
dred pounds in weight, and the flesh is used as food in many 
of the islands, one being sufficient for many people. An 
ornamental arrangement of shells is also shewn under a 
glass-shade — the shells being made up into flower pat- 
terns. Small cases on the table contain limpets (Pa- 
tella) % noted for the tenacity with which they adhere to 
the surfaces on which they are found, oysters of different 
sorts, different sizes of the lemon or elongated land- 
snails (Bulimus) — a common colonial form — and other 
varieties of colonial snails, such as the apple-snails 
(Ampullaria) , etc. The eggs of Bulimus are also 
shewn, presenting a curiously bird-like form, being often 
mistaken for them, though the surface is much rougher. 
Along each side of this central row of tables, and slightly 
raised from the floor, are arranged large polished speci- 
mens of the chief woods of the colony. The names, 
common and scientific, where possible, have been affixed 
