The anomalous position of the vent in Amblyopsidæ occurs again in an equally singular fish, Aphredoderus sayanus, which is found in the same waters throughout the same region in which Chologaster occurs. It would seem as if these lowland fishes of the southern swamps were remains of a once much more extensive fauna.
No fossil allies of Chologaster are known.
Kneriidæ, etc.—The members of the order of Haplomi, recorded above, differ widely among themselves in various details of osteology. There are other families, probably belonging here, which are still more aberrant. Among these are the Kneriidæ, and perhaps the entire series of forms called Iniomi, most of which possess the osteological traits of the Haplomi.
The family of Kneriidæ includes a few very small fishes of the rivers of Africa.
The Galaxiidæ.—The Galaxiidæ are trout-like fishes of the southern rivers, where they take the place of the trout of the northern zones. The species lack the adipose fins and have the dorsal inserted well backward. According to Boulenger these fishes, having no mesocoraoid, should be placed among the Haplomi. Yet their relation to the Haplochitonidæ is very close and both families may really belong to the Isospondyli. Galaxias truttaceus is the kokopu, or "trout," of New Zealand. Galaxias ocellatus is the yarra trout of Australia. Several other species are found in southern Australia, Tasmania, Patagonia, and the Falkland Islands, and even in South Africa. This very wide distribution in the rivers remote from each other has given rise to the suggestion of a former land connection between Australia and Patagonia. Other similar facts have led some geologists to believe in the existence of a former great continent called Antarctica, now submerged except that part which constitutes the present unknown land of the Antarctic.
As intimated on p. 253, Vol. I, this distribution of Galaxias with similar anomalies in other groups could not if unsupported by geological evidence be held to prove the former extension of the Antarctic continent. Dr. Boulenger[[12]] has recently shown that Galaxias lives freely in salt water, a fact sufficient to account for its wide distribution in the rivers of the southern hemisphere.
[12]. Dr. Boulenger (Nature, Nov. 27, 1902) has the following note on Galaxias: "Most text-books and papers discussing geographical distribution have made much of the range of a genus of small fishes, somewhat resembling trout, the Galaxias, commonly described as true fresh-water forms, which have long been known from the extreme south of South America, New Zealand, Tasmania, and southern Australia. The discovery, within the last few years, of a species of the same genus in fresh water near Cape Town, whence it had previously been described as a loach by F. de Castelnau, has added to the interest, and has been adduced as a further argument in support of the former existence of an Antarctic continent. In alluding to this discovery when discussing the distribution of African fresh-water fishes in the introduction to my work 'Les Poissons du Bassin du Congo,' in 1901, I observed that, contrary to the prevailing notion, all species of Galaxias are not confined to fresh water, and that the fact of some living both in the sea and in rivers suffices to explain the curious distribution of the genus; pointing out that in all probability these fishes were formerly more widely distributed in the seas south of the tropic of Capricorn, and that certain species, adapting themselves entirely to fresh-water life, have become localized at the distant points where they are now known to exist. Although as recently as October last the distinguished American ichthyologist D. S. Jordan wrote (Science, xiv, p. 20): 'We know nothing of the power of Galaxias to survive submergence in salt water, if carried in a marine current': it is an established fact, ascertained some years ago by F. E. Clarke in New Zealand and by R. Vallentin in the Falkland Islands, that Galaxias attenuatus lives also in the sea. In New Zealand it periodically descends to the sea, where it spawns, from January to March, and returns from March to May. In accordance with these marine habits, this species has a much wider range than any of the others, being known from Chile, Patagonia, Tierra del Fuego, the Falkland Islands, New Zealand, Tasmania, and southern Australia.
"I now wish to draw attention to a communication made by Captain F. W. Hutton in the last number of the Transactions of the New Zealand Institute (xxxiv, p. 198), 'On a Marine Galaxias from the Auckland Islands.' This fish, named Galaxias bollansi, was taken out of the mouth of a specimen of Merganser australis during the collection excursion to the southern islands of New Zealand made in January, 1901, by His Excellency the Earl of Ranfurly.
"It is hoped that by giving greater publicity to these discoveries the family Galaxiidæ will no longer be included among those strictly confined to fresh waters, and that students of the geographical distribution of animals will be furnished with a clue to a problem that has so often been discussed on insufficient data. As observed by Jordan (l. c.), all anomalies in distribution cease to be such when the facts necessary to understand them are at hand.'
"Of the fresh-water species of Galaxias, eight are known from New Zealand and the neighboring islands, seven from New South Wales, three or four from south Australia, one from west Australia, two from Tasmania, seven from South America, from Chile southwards, and one from the Cape of Good Hope."