ALBERT

Description: The distribution of fresh-water fishes like that of other groups, has been widely utilized by zoogeographers, but with widely divergent acumen and success. At one extreme are those non-ichthyologists who have uncritically utilized for evidence certain groups whose distribution happens to support whatever theory they may be espousing. At the other extreme is the work of careful ichthyologists like DE BEAUFORT (1913) and REGAN (1922) whose thorough knowledge of the groups with which they are working demands the most careful consideration of their conclusions. However, no zoogeographer who utilizes the evidence of diverse groups can be familiar at first hand with all of them, and the difficulty facing such workers is that of seeking out the really dependable evidence in those groups he does not know well. Aside from the difficulty of selecting dependable authorities or systematic works, the zoogeographer desiring to use the evidence of fresh-water fishes has another troublesome matter to contend with. This is the differing tolerance of salt-water exhibited by different groups of fresh-water fishes. As one example, and one which has frequently troubled zoogeographers, we may mention the Galaxiidae, fresh-water fishes of Southern South America, Africa, Australia, and New Zealand, whose distribution has been held by some to be evidence for continental drift or southern intercontinental land-bridges. Ichthyologists now know that these fishes are, as a group, salt-tolerant and possibly either anadromous or catadromous, and that they are not really strong evidence for continental connections simply because it seems possible that they may cross ocean barriers.