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NOTE ON PROTECTIVE EESEMBLANCE, ETC., IN POST- 
LAEVAL STAGES OF SOME CAPE FISHES. 
By J. D. F. aiLCHRisT, M.A., D.Sc, Ph.D. 
The eggs and larvae of about thirty species of Cape sea fishes are now 
known, and several eggs and larvae have been described the origin of which 
are at present doubtful. A few post-larval stages are known, and some of 
them exhibit interesting characteristics in the form of adaptation, apparently 
to tide over the dangerous stage between the larval and the adult life. 
These have been noted in the case of the stock-fish, the leer-fish and others, 
but the most striking case of obvious adaptation has been found in those of 
the needle-fish (Hemirhamphus calaharicus) . This fish is one of those which 
may be designated the warm-water fishes of the Cape, which are found 
chiefly in the warm waters of the east coast and extend round on the south 
coast to about Cape Agulhas. Beyond this point, to the west, it is scarce, 
and has not yet been recorded from the west coast. It appears to frequent 
the shallow lagoons and tidal rivers, and is often found there in such 
abundance that it is of some commercial value. The eggs and larval stages 
of the fish are not known, but the post-larval stages prove to be abundant 
in the shallow waters at some localities, and can readily be observed when 
their peculiar habits are known. These young forms, though small (about 
an inch in length), are yet so far advanced as to leave no doubt but that 
they are the young of the needle-fish. 
On a recent occasion, while procuring the eggs and young of fish in 
the lagoon at Knysna, Mr. Henkel, Conservator of Forests, drew my 
attention to the peculiar behaviour of certain small fish-like animals in 
the water. They could only be detected if approached cautiously or by 
remaining perfectly still for some considerable time. They were then seen 
very plainly as small fish swimming about actively in groups of a dozen 
or more. The lagoon, or harbour, at Knysna is a large area of water 
extending inland from the sea for several miles. On the mud-fiats and 
banks of this lagoon are extensive areas on which a dense growth of a weed 
(Zostera ?) occurs. During the summer months fragments of this weed are 
very abundant in the river, so abundant that, in tow-netting for fish eggs, 
the net was invariably clogged with it in a short time, and fragments, 
