Scientific results of the trawling expedition of H.M.C.S. "Thetis" off the coast of New South Wales, in February and March, 1898, Tunicata

Abstract

The collection of Crustacea obtained during the cruise of the " Thetis" proves to be exceptionally rich in forms either new to science or to the fauna of New South Wales. ' Of the forty-five species herein dealt with, twenty are additions to the fauna; nine of which are described as new. The above remarks apply to the higher Crustacea only; the .lower, when thoroughly worked out, will I ,believe yield a far larger proportion of novelties. Although the" Thetis" collection ,shows the,coastal waters to be so rich, it probably includes but a small portion of our Crustacean fauna. It must be remembere0 that the "Thetis" Trawling Expedition was fitted out to test the deeper waters off the coast for fish alone; all other organisms were considered of secondary importance. Still Mr. Waite on several occasions contrived means to secure representatives of the smaller forms of life, and succeeded in preserving a very large quantity of material which will yield a rich harvest when fully investigated. The extreme richness of the fauna of Port Jackson is now generally acknowledged, but many still entertain the idea that the waters off the coast are deficient in fish food, and that there is a scarcity of minute living organisms such as abound in other parts of the ocean. Considering our limited knowledge of the fauna of the deeper waters of the coast, there seems to be some justifi- 'cation for this idea; but if the fauna as at present known is taken into, account it is evident that it i~ scarcely,correct, and when the coastal area has been thoroughly explored, there can- not be the least doub~ that its waters will be found as ,richly endowed with life as in a~y part of the world. In ilupport ,of this view mention may be made of the vast streams of Pelagic life which visit these shores annually. This" cycle of matter in the sea" makes its appearance about the middle of January, and is more or less present on the coast until the latter end of June. n consists of millions of living organisms, moving along the crowded sea animal streets, and contains representatives-either as young or adults-of almost all groups of marine life. The number of different species wandering about in one of these sea thoroughfares must be very great; still our knowledge of them is scanty indeed, and will remain so until proper means are taken for their investigation. The results of the" Thetis" Expedition are such that we may reasonably expect to meet with an extremely rich bottom faUlia off the coast when it has been systematically explored, and in this connection it is hoped that the Government will furnish the means for a mote complete investigation of our Jllarine fauna, particularly ·in regard to the organisms which constitute the food of fishes. As an instance of the remarkable wealth of life, at moderate depths off the coast, mention may be made of a 8tone that was acquired by the Museum in May, 1898. See Plate xxxii. In order to fully realise the number of organisms living on this stone, it will be necessary to give some account of how it was obtained and the treatment it subsequently received. A man while fishing in 30 fathoms off Long Reef, near Manly, suddenly found his line fast, and after much tugging, finally succeeded in hauling it up. When the leaded end neared the surface he saw that his line had become entangled round the stem of a large " sea-fan," the base of which was attached to the corner of a stone nearly thirty pounds in weight. The stone was placed in the bottom of the boat, and when the fisherman returned home he took it with him for the sake of the beautiful" sea-fan." During this rough handling many small active Gasteropods, Annelids, Amphipods, Isopods and Echinoderms doubtless escaped. Next day this object was brought to the Museum, and was handed over to me for preservation. It was washed in fresh water to remove the salt, and the organisms disturbed were carefully collected. The stone is irregularly oval in shape, measuring 35 cm. in length, 26 cm. in breadth, and 10 cm. in height or thickness. The Gorgonia or "sea-fan" which is attached at one corner is a species of Juncella, measuring 90 cm. in height, 60 cm. in breadth; the greatest diameter of the stem does not exceed 8 mm., while its base forms a circle of about 30 mm across. The whole of the upper surface of the stone is completely covered with animal growths, so that it is impossible to see any portion of the original surface; one patch about the size of a half- crown appeared to be like the naked rock, but is found to be a dried Compound Ascidian. The smaller objects in the following list have been determined by means of a hand-lens; the specimens are so numerous and so doselypacked that it is difficult to bring them into focus, owing to a miniature forest of projecting stems, branches and worm tubes. Were it possible to apply the microscope direct the number of species might be considerably increased; these remarks apply more especially to the Polyzoa, which cannot be determined in their present position, and their removal from the stone would 'entail their destruction a~ well as the objects near t~em. The following is a list of the species attached to the stone, and also of the free or active ones, as ascertained by an elamination of the residue of the fresh-water washing.