44 MEMOIBS OF THE QUEENSLAND MUSEUM. THE OCCURRENCE IN BRISBANE RIVER OF THE NEW ZEALAND AMPHIPOD, PARA^ COROPHIUM EXCAVATUM (G. M. THOM-SON). By Chas. Chilton, M.A., D.Sc, M.B., CM., LL.D., F.L.S., C.M.Z.S.. Hon. Memblk Roy. Soc. N.S.W., Professor of Biology, Canterbury College, New Zealand. (With Text-figures Nos. I to XIX.) Towards the end of 1918, I received from Professor T. Harvey Johnston, of the University of Queensland, and honorary Zoologist to the Queensland Museum, a few Crustacea from Brisbane River, sent chiefly because of the boring Isopod, Sphceronia terebrans Bate, which was doing considerable destruc-tion in timber immersed in the water. Among the specimens, however, were numerous examples of a small amphipod evidently belonging to Coropliiura or some allied genus. The male of this species first attracted my attention because of the character of the second gnathopod and the possession of a lobe on the inner side of the end of the penultimate joint of the peduncle of the lower antenna. Later on when I came to examine the females, which differed in the structure of the second gnathopod and in having no lobe on the antenna, I was struck by their resemblance to the descriptions of Paracorophium excavaturn (G. M. Thomson), an amphipod found in brackish waters of New Zealand. In that species no sexual differences had hitherto been described. However, I found on closely examining specimens in my collection that there were some males among them having the characters of the second gnathopod and the lobe on the lower antenna quite similar to those of the Brisbane specimens, and careful comparison shows conclusively that the Brisbane specimens belong to the same species as the New Zealand. I take this opportunity of giving a fuller account of the species than has hitherto been published and of describing the differences between the male and the female. Paracorophium excavaturn was described by Mr. Gt. M. Thomson in 1884, under the name Corophium excavaturn, from specimens obtained in Brighton Creek, near Dunedin, the water of which he described as being salt. A little later I received some specimens from Napier, and in January, 1890, I collected a number at Brighton itself at a time when the water in the estuary was nearly fresh or only slightly brackish ; in 1894 I obtained a few specimens from Nelson, also in brackish water. In 1902 Messrs. Lucas^ and Hodgkin obtained specimens ' Keith Liieas, A Bathymetrieal Survey of the Lakes of New Zealand, Geographical Journal for May. and June, 1904.