I have already shown that the secretion of the five large cardiac sacs of the stomach of Uraster rubens contains uric acid; and consequently these sacs are considered to be the necessary apparatus for eliminating the nitrogenous products of the waste of the tissues, “it is possible that the uric acid arrived into the starfish's stomach in the interior of small mussels, &c., whose excretory organs contain that body, and of which as food the starfish appears to be very fond: anyhow, such a source of the uric acid must be eliminated before Griffiths’ conclusion can be accepted; for obviously, if the presence of urates were demonstrated in the gastric contents of an individual who had recently supped off oysters, it would by no means follow that the stomach was the organ whereby the individual excreted his urates.” Certainly not; but Mr Durham has overlooked the fact that if the uric acid had been introduced along with the food, I should also have found urea in the contents of the starfish's stomach; but I conclusively proved that urea was absent.