On a former occasion I had the honour of laying before this learned Society a collection of Molluscs and Zoophytes, from the northern part of the Bay of Bengal; I shall to-day take the liberty of calling their attention to some sketches of fishes from the same locality, and the estuaries of the Ganges, which I had an opportunity of making during my sojourn there, while discharging the medical duties on the Honourable Company's surveying vessels. By reference to the ichthyological works, from different Indian localities, of Dr. Russell, Dr. Hamilton, Baron Cuvier, and Mr. Bennet, it would appear that at least one-third, perhaps one-half, out of upwards of a hundred species, which I examined between Calcutta and the twenty-first degree of north latitude, are not noticed by the above authors. Dr. Hamilton, indeed, in the introduction to his work upon the Gangetic fishes, is of opinion, that while in the rivers above, where the tide reaches, not more than one kind in five has escaped his notice, of those found in the estuaries he has not probably described above a half, a great number of which have been noticed by Dr. Russell. The fact is, I have observed many species, which, inhabiting a more southern latitude, are brought up towards the mouths of the Ganges, by the strong flood-tide prevailing during full moon, while others only temporarily enter the rivers during the spawning season. Thus many fishes, found in abundance by Russell on the Coromandel coast, are very scarce, or not met with towards the northern part of the Bay of Bengal, and of those species from Ceylon, figured and described by Mr. Bennett, I have observed none.