FRESH-WATER PISHES— MYERS 35X 



America, and the poeciliid fauna is richer than either the North or 

 South American. I suspect the family to be of fairly recent origin 

 and it seems probable that the forms now present in the southern 

 United States are late immigrants from the south. They like warm 

 water too much to have enjoyed Pleistocene Florida in the company 

 of pike or muskellunge. 



5. GENERAL 



There is not a scrap of factual evidence, fossil or recent, on which to 

 postulate a North American origin of the present South American 

 fresh-water fishes. At this seemingly pontifical pronouncement^ I can 

 see some of the proponents of the northern-origin-for-everything 

 theory cast their eyes toward that good old standby, the Green River 

 Eocene of Wyoming. I am perfectly aware that the common occur- 

 rence of representatives of the existing South American family Osteo- 

 glossidae, and of the percomorph genus Priscacara, in that and other 

 Eocene formations, has been held time and again to denote where 

 South America got its osteoglossids and cichUds.'^ I have already 

 said that I do not believe the osteoglossids can give us much informa- 

 tion on the Tertiary distribution of the bony fishes, because of their 

 age and probable wide Eocene or pre-Eocene distribution. AustraUa 

 was cut off from Asia before the origin of any of the families of domi- 

 nant fresh-water bony fishes, yet it has a still living osteoglossid which 

 is close?- to the Gh'een River Phareodus than the latter is to the living South 

 American genera. This single species of Scleropages forms the total 

 living true, fresh-water, bony fish fauna of Austraha and Papua and it 

 finds its only very close relative in another living species of Scleropages 

 west of Wallace's Line — and this genus is the only example of the 

 primary division of fresh-water fishes that exists on both sides of this 

 ancient barrier. Both species of Scleropages are extremely ancient 

 rehcts of the days before Ostariophysi existed. This will, I think, 

 make it clear why I reject the mere presence of an osteoglossid in a 

 North American Eocene formation as evidence of a northern derivation 

 of the South American Ostariophysi.^^ 



Priscacara of the Green River Eocene was described by Cope as a 

 cichhd and is considered to be one by two students of South American 

 fishes (Haseman, 1912; Pearson, 1937). Our foremost authority on 

 the cichlids (Regan, 1908, p. xiv), however, decided that Priscacara 

 was not a cichlid, and I agree with him. To me it seems most likely 

 that the priscacarids were either sunfishes, as Regan (1916) decided 



"See especially Matthew (1915, p. 298). Matthew's reasoning, and information, is here very faulty. 

 Lepidosteus, which he in some way imagined to be a Neotropical group, is Holarctic. Arius is a marine 

 ariid not related either to the South American pimelodid Phradocephalus or to Rhineastes of the Bridger, 

 which belongs with the living North American Ameiurids (see Regan, 1922). 



'» Fossil osteoglossids are known, outside the Green River, from the probably Eocene Alergelschicfer 

 (Sanders, 1934) of Sumatra (Musperia and Scleropages). Brychaetus is known from the marine Eocene 

 London Clay and may not be an osteoglossid. 



