228 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



America, KneviidcE of Africa, Dalliidce of Alaska and Siberia, and the 

 dominant PceciHidcs of the tropical fresh waters, the Esocidce of the north 

 temperate zone, and the Scopelidcs of the deep sea. By Gill, on the other 

 hand, they are placed in the order of Malacopterygii with the Clupeoids 

 and Salmonoids. 



Of the Apiochitonidce there are two genera, Aplochiton with an unde- 

 termined number of species in the Patagonian region, and Prototyoctes 

 with three species, one in Queensland, one in South Australia and one in 

 New Zealand. 



Of the Galaxiidce there are two genera, Neochanua [apoda) from New 

 Zealand, where it frequently burrows in damp clay aw-ay 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 Petromyzonidce are found in all temperate 

 fresh waters and seas, in both the northern and southern hemispheres. 



The distribution of the tw^o 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 distribution. If there was a continental mass 

 connecting South America with New Zealand and Australia fit to be 

 inhabited by fishes, there must have been an abundant and diverse fish 

 fauna which has disappeared. If the antarctic continent depended entirely 

 for its existence on the evidence from the distribution of the fresh water 

 fishes, its existence would be very highly theoretical and precarious. 

 Concerning the distribution of Ga/axias, Boulenger says : 



"The fact that certain species of Galaxias live both in fresh water and 

 in the ocean suffices to explain the curious distribution of this small family 

 without the necessity of appealing to the existence in the past of an 



