10. Gasteropelecus stellatus Kner, an Extremely Swell Characin. This is connected by many intermediate forma with normal-shaped species.
interesting Diplomyste, which is found on the northern border of Patagonia, but is not a derivative of the tropical American fauna. It is a relict of the original catfishes, in which the maxillary is still functional as a tooth bearer. Here belongs also Nematogenys, a catfish related to Pygidium. Like the members of group 2, these species are confined to the northern fringe of the Patagonian area.
4. There remain unaccounted for the members of the Aplochitonidæ, Galaxiidæ and Petromyzontidæ, chiefly of southern Patagonia.
Of the Aplochitonidæ there are two genera, Aplochiton, with an undetermined number of species in the Patagonian region, and Prototroctes, with three species, one in Queensland, one in South Australia and one in New Zealand.
Of the Galaxiidæ there are two genera, Neochanna (apoda) from New Zealand, where it frequently burrows in damp clay away from water, and Galaxias, with about 30 species, from New Zealand, New South Wales, South Australia, Tasmania, Cape of Good Hope, southern South America and the Falkland Islands. The Petromyzontidæ are found in all temperate fresh waters and seas in both the northern and southern hemispheres.
The distribution of the two former families is of interest in connection with the theory of a former antarctic continent connecting the land masses in which they are found. In favor of a former land connection it may be argued, and with justice, that while these species descend to the sea, the probability that any pair of individuals should migrate from Cape Horn to New Zealand, or vice versa, is highly improbable. (This objection loses some weight if they spawn in the sea, as is reported.) There are no intermediate places that might be colonized and serve as new centers of distribution. It may further be urged that these species could readily have been distributed to their present homes by migration from stream to stream along a continuous coast line or on a land-wave moving from one place to another. An obvious objection comes from the paucity of the forms with this peculiar dis-
