Account of Soundings taken by the “Challenger” Expedition.
The limbs are two pairs of paddles, very similar to each other in shape, and very unlike the ordinary fins of fishes, resembling more the appearance of the paddles of an Ichthyosaurus. The teeth of the Barramunda consist of hard plates, four above and two beneath, and they afford the chief point of interest which this remarkable fish possesses for the palæontologist, as they exactly resemble the fossil teeth described under the name of Ceratodus. It is now easily understood why nothing but the teeth and the ganoid scales ot the extinct fish should have been preserved. A few specimens of the Barramunda were obtained by Professor Wyville Thomson on his recent visit to Queensland, while H.M.S. “Challenger” was in Sydney, and among them this specimen, which he brought specially for this Museum, being one of the most important of the many contributions we received from the “Challenger” expedition.
The “Challenger,” after leaving the Cape of Good Hope, went as far south as 67°, close to the ice barrier, and visited Kerguelen Land, where some interesting photographic views that were exhibited had been taken. An interesting point, illustrated by microscopic specimens on the table, is that at a depth of 2600 fathoms, close to the ice, the sea-bottom is composed of siliceous Diatoms, while in the same depth further north the deposit is formed of calcareous Foraminifera. The latter appear to have been dissolved in the cold polar under-current, so that when they are reached in the deep soundings in more temperate latitudes only a fine mud is found, composed of the small percentage of insoluble matter which the calcareous skeletons contain. In taking soundings for the telegraph cable line, the “Challenger” ran a straight course from Sydney to Cook Strait. On leaving the Australian coast the soundings showed a gentle gradient to the great depth of 2600 fathoms, which,
with only one shoal, was carried to within a few hundred miles of our coast, when the soundings rather suddenly decreased from 15,000 to 4000 feet. This submarine precipice lies about 300 miles from land opposite Cape Farewell, but there is reason to believe that further south it approaches the coast, and at Milford Sound is close to the shore. On this plateau the dredge was used, and some interesting specimens were obtained. Of these, several new species of fish had been handed to Dr. Hector for description. These were exhibited, and their characters described at length. They comprised, among others, Trachichthys intermedius, Scorpœna barathri, Platystethus abbreviatus, Macrurus armatus, Pseudorhombus boops, and some others. Dr. Hector, also, in passing described several other new fish. Among them were Plectropoma huntii, from the Chatham Islands; Maurolicus borealis, from Preservation Inlet, a former specimen of which had been obtained in Milford Sound in 1863; and Leptoscopus robsoni, from Cape Campbell. (Transactions, p. 245.)