, 1891-05-09

there be any truth at all i'll this chronicle
gy of the Biologists, this colour, which
defeS even the tooth OF all-cOnsuming
Time, cannot owe it's immol tality to mere
chemical combination. 1t must derive its
imdestructibility from some source unknown
to Science. This is one OF the sacred
secrets of the rocks" of which the poet
talks, which Nature has not yet whispered
into the listening ear of man Or, as Lord
Dundreary would say, cit is one of those
things which no fellow can understand"
IN size, shells vary from that of a small
grain OF sand, scarcely visible to the naked
eye, as in StoaStOma, a Jamaica snail, up
to the Giant Clam Nridacna Gigas) which
weighs from FIVE to six hundred pounds.
! am sorry that this, the great boss Of all
shells, is not a Creole, 1t comes from the
Indian Ocean. The largest West Indian
shell that / have seen was a helmet-shell
in Santa Cruz, which was almost as big as
a lady'S bandbox and would have fitted the
head of Goliath,
It is rather a common belief that life
types have dwindled in these our degene-
rate days. But that is u mistake. 1t is
true that one is not likely nowadays in
taking his mornings constitutional stroll
to collide with q carnivOrOus lizard fifty
feet long, as tall as a carthOrse, and in a
SlFdl hurry " uHS OlCuhl hHU u GAC
existing Greenland whale is the largest
vertebrate ever seen on our planet and
the rocks contain no shell that can COM
pare in size with tho Tridaena Gigas.
The Republic Of Venice presented an
enOrmOu specimen of it TO the French
King Francis the First, who gave it TO
the Church OF st. Sulpice III Paris, where
it is used to hold holy water, Lowell
Reeve says that a still bigger one, which
would require a wagon and a pair of
horses for its re mOval, adoin M an oyster.
shop in London.
BY way Of contrast for tins Brobdin-
nagian, note these tiny objects TWO are
Kitufonians, the Phasianella tesseIata
and a RiSSOa. The beauty of the former
when viewed through II magnifying glass
cOmpenSateS for its Lilipntian proportions.
1t well deserves its generic name, for its
v~ariegated and brightly painted pattern
is very suggestive OF the plumage of a
handsome bird. The other one is not a
West Indian. 1t is the RiSsoa exigua from
France. It's only excuse for being pre-
scented to yOu on this OCCASION is that it
is such a little one.
II was supposed until quite recently that
the she'll OF a mOlluScOuS creature was
only an exud&tiOn from it's mantle of an
animal juice holding a large proportion of
mineral matter in solution. 1t is now
known, chiefly owing to the researches of
DR.. Carpenter, that the substance of shells
consists of organised membranes of def
mite formation but varying in the different
classes or even genera of the MOllusca.
These two diagrams (Which might for
instance have been taken from sections
of shells like these st. Kits species Pima
ramulOsa and Conus nebulosus), illustrate
the texture Of the two principal types of
shells the LameIlibranchiate Bivalye
and the Univalye. The substance of the
first is composed of h%exagonaI pillars like
the basaltic columns of the famous Fin
gaPS Cave. They are seen here in trans
verse section. The second diagram, also
a transverse section, Shews three layers
of plates set closely together like packs of
cards AMI so arranged that the middle
layer is at right angles to the outer and
inner strata. Each plate consists of
priSms fixed ~Obliquely at an angle of forty
Ave degrees and disposed in lines which,
if prolonged, would cut at right angles
the corresponding lines of the adjacent
plates on either side. This complicated
construction gives wonderful strength in
proportion to weight and amount Of mate
rial. The shell Of the Brachoipodous Mol
lusc is built on quite a different pattern
again. Here is % diagram Of a vertical
section of q fossil brachiopol nearly al led
to this pal@ozic Terebratula sent me-, as
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