IN a note occurring in your last issue (p. 348), mention is made of an interesting fact with which zoologists have for some time been familiar, namely, that the medusa characteristic of Lake Tanganyika exists at present in the Victoria Nyanza also. As it seems to be suggested that this discovery is in some way or another adverse to the theory of the origin of a portion of the fauna of Tanganyika for which I have been responsible, you will perhaps allow me space to point out that, so far from the fresh knowledge being in any way antagonistic to the view in question, the existence of the jelly fish in other lakes beside Tanganyika is exactly what one would, and did, anticipate, supposing the halolimnic theory to be correct.