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Geology of Sydney. 
Graphite (Gr. grapho, I write). Mineral carbon. (The 
familiar “ blacklead ” is graphite). 
Graptolitidse (Gr. grapho , I write ; lithos , a stone). An 
extinct sub-class of the Hydrozoa. 
Gymnosperms (Gr. gumnos , naked ; sperma , a seed). The 
Conifers and Cycads, in which the seed is not protected 
within a seed-vessel. 
Haematite (Gr. haima , blood). Sesqui-oxide of iron ; has 
a red streak. 
Heterocercal (Gr. heteros , diverse; kerkos , a tail). Applied 
to the tail of Fishes when it is unsyimnetrical, or com- 
posed of two unequal lobes. 
Hornblende. A mineral which is silicate of magnesia, lime 
and iron; usually green or dark in colour; chemically 
identical with, but mineralogically distinct from augite. 
Ichthyosauria (Gr. ichthus, a fish ; saura , a lizard). An 
extinct order of Reptiles. 
Iguanodon ( Iguana , a living lizard ; Gr. odous, a tooth). 
A genus of Deinosaurian Reptiles. 
InYertebrata (Lat. in, without; vertebra, a bone of the back) 
Animals without a spinal column or backbone. 
Labyrinthodontia (Gr. laburinthos , a labyrinth ; odous , 
a tooth). An extinct order of Amphibia, so called from 
the complex microscopic structure of the teeth. 
Lepidodendron (Gr. lepis, gen. lepidos , a scale ; dendron , 
a tree). A genus of extinct plants, so named from the 
scale-like scars upon the stem, left by the falling ofi 
of the leaves. 
Lepidostrobus (Gr. lepis , a scale ; strobilos , a fir-cone). A 
genus founded on the cones of Lepidodendron. 
