NATURAL HISTORY
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other schooling species appeared seasonally in commercially ex- ploitable quantities. In the course of fisheries development, however, the abundance of these resources (with the exception of certain isospondylous fishes) began to diminish-possibly due to an in- creasing disturbance of the local marine environment. The full extent of Hong Kong's marine fauna is difficult to assess but the diverse varieties of fish, crustacea, cephalopod, mollusc and seaweed in- dicate that the number of species involved is certainly very high. The discharge of the largest freshwater system in South China to the west, and the prevailing Taiwan Current from the northeast, have created a situation where the westerly sector of Hong Kong has a predominately brackishwater fauna, while the eastern sector has a genuine marine fauna. A notable marine animal which has been successfully introduced in the Deep Bay area is the Japanese oyster, Crassostrea gigas. It is now being cultivated.
FLORA
The flora of the Colony is tropical, although at about the northern limit_of_tropical flora. After centuries of cutting and burning most of the original arborescent vegetation on the mountainsides has been replaced by herbaceous cover, but in the ravines and on sheltered northern slopes a flora rich in flowering shrubs, low trees and ferns persists. Few high trees are to be found except in the fine fung shui groves preserved around many villages in the New Territories. A great variety of plants in Hong Kong bear flowers of exceptional beauty or fragrance.
The Bauhinia Blakeana, which grows on a medium-sized ever- green tree known as the Hong Kong orchid tree, is among the finest of the Bauhinia genus anywhere in the world and has been adopted as Hong Kong's floral emblem. Named after a former Governor, Sir Henry Blake, it was discovered in 1908 by the Fathers of the French Foreign Missions at Pok Fu Lam. Its origin is unknown and it is a sterile hybrid never producing seed. Another related species is Bauhinia glauca, climbing by means of tendrils, with bunches of pink flowers of sufficient beauty to merit cultivation as a covering for trellises and porches.
There are several species of camellia growing wild on the island and the mainland. All but one have white flowers; the one with
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