[Footnote 1:  “A curious species, which is of a light brown above, white underneath; very broad and thin, and has a peculiarly shaped tail, half-moon-shaped in fact, like a grocer’s cheese knife.”]

Acalephae.—­Acalephae[1] are plentiful, so much so, indeed, that they occasionally tempt the larger cetacea into the Gulf of Manaar.  In the calmer months of the year, when the sea is glassy, and for hours together undisturbed by a ripple, the minute descriptions are rendered perceptible by their beautiful prismatic tinting.  So great is their transparency that they are only to be distinguished from the water by the return to the eye of the reflected light that glances from their delicate and polished surfaces.  Less frequently they are traced by the faint hues of their tiny peduncles, arms, or tentaculae; and it has been well observed that they often give the seas in which they abound the appearance of being crowded with flakes of half-melted snow.  The larger kinds, when undisturbed in their native haunts, attain to considerable size.  A faintly blue medusa, nearly a foot across, may be seen in the Gulf of Manaar, where, no doubt, others of still larger growth are to be found.

[Footnote 1:  Jelly-fish.]

[Illustration:  PHYSALUS URTICULUS.]

Occasionally after storms, the beach at Colombo is strewn with the thin transparent globes of the “Portuguese Man of War,” Physalus urticulus, which are piled upon the lines left by the waves, like globules of glass delicately tinted with purple and blue.  They sting, as their trivial name indicates, like a nettle when incautiously touched.

Red infusoria.—­On both sides of the island (but most frequently on the west), during the south-west monsoon, a broad expanse of the sea assumes a red tinge, considerably brighter than brick-dust; and this is confined to a space so distinct that a line seems to separate it from the green water which flows on either side.  Observing at Colombo that the whole area so tinged changed its position without parting with any portion of its colouring, I had some of the water brought on shore, and, on examination with the microscope, found it to be filled with infusoria, probably similar to those which have been noticed near the shores of South America, and whose abundance has imparted a name to the “Vermilion Sea” off the coast of California.[1]

[Footnote 1:  The late Dr. BUIST, of Bombay, in commenting on this statement, writes to the Athenaeum that:  “The red colour with which the sea is tinged, round the shores of Ceylon, during a part of the S.W. monsoon is due to the Proto-coccus nivalis, or the Himatta-coccus, which presents different colours at different periods of the year—­giving us the seas of milk as well as those of blood.  The coloured water at times is to be seen all along the coast north to Kurrachee, and far out, and of a much more intense tint in the Arabian Sea.  The frequency of its appearance in the Red Sea has conferred on it its name.”]