THE LACCADIVES AND THE WEST COAST. 467 
preference bare dark rocks and reefs, their extremely conspicuous 
white plumage may have been in many ways disadvantageous 
to them. It would not only be that their enemies would more 
readily discern them, but that their prey also would be less likely 
to permit their approach. Any variation, therefore, towards a 
grey or dusky tint, such as a marked change in diet, might well 
produce, would be a distinct advantage to the individuals thus 
favored, and the descendants of these, if they retained this 
peculiarity, would be likely in time to supersede the original race. 
Dusky varieties would gradually gain ground and become the 
predominant forms as we now see them. 
At the same time the variety does not even yet appear to 
have become well fixed, young white birds, spotted more or 
less with dusky, appeared to be common, and a certain portion 
of these revert later in life to the pure original type. 
It is certain not only that the white birds in both species 
are far less common than the slaty ones, but also that they 
are far more wary ; I have tested this myself dozens of times, 
so that they at least are conscious that there is something 
about them that makes it more dangerous for them than for 
the others to allow an enemy to approach. As a matter of fact 
you invariably notice these at a distance of a quarter of a mile, 
while you may row within twenty yards of one of the grey birds 
as he sits motionless amidst the dusky surf-beaten rocks with- 
out ever seeing it. 
930.—Ardeola Grayi, Sykes. 
We only met with the Indian Pond Heron on Amini ne 
Cardamum, and there we only saw two or three examples. 
931.—Butorides javanicus, Horsf. 
We saw and shot a single specimen of the Green Bittern 
at Cardamum. 
986 b1s.—Sterna albigena, Licht. (Nomencl. Mus. 
Berol., p. 98;) 
Firing into a crowd of small Terns, Dr. Armstrong killed 
two birds of this species, together with a number of lesser 
Terns at Cherbaniani reef, on the 13th February. Neither of 
the specimens were adult, and the lower surface has only a 
certain number of the feathers of the breast and abdomen a 
blue smoky grey ; moreover, the forehead and greater part of the 
crown are greyish white more or less speckled with blackish 
brown; and owing to the imperfect development of the black 
of the head, the white cheek stripe is only imperfectly marked. 
Independent of the smoky grey under surface this species 
