270 A HISTORY OF FISHES 



including Australia, New Guinea, and all the islands of the 

 Indo-Australian Archipelago lying east of a line running 

 between Borneo and Celebes and separating the islands of 

 Bali and Lombok; (2) Madagascar; (3) a Neotropical region, 

 including Central and South America; (4) an African or 

 Ethiopian region; (5) an Indian region, including India, 

 South-eastern Asia, and the islands of Java, Sumatra, and 

 Borneo; (6) a Palaearctic region, including Europe and Asia 

 as far south as the Himalayas and the River Yang-tse-Kiang; 

 and (7) a Nearctic region, which includes Canada, the United 

 States, and the greater part of Mexico. 



The Australian region presents features of particular interest, 

 and the hypothetical boundary known as Wallace's Line, 

 running between Borneo and Celebes and Bali and Lombok, 

 probably represents the origmal line of separation when 

 Australia was severed from the Asiatic continent. This separa- 

 tion, which is known to have taken place at a very remote 

 period, probably at or before the beginning of the Tertiary, 

 has resulted in the almost complete absence of true fresh-water 

 fishes in the Australian region, since thje severance must have 

 occurred before the Ostariophysi had even begun to evolve. 

 In this region there are a number of fresh-water genera and 

 species closely alhed to marine forms, such as Gobies, Sea Perches, 

 Herrings, Grey Mullets, Sand Smelts, etc., but there are no 

 peculiar fluviatile families. The only true fresh-water species 

 are two in number, and both belong to very archaic groups 

 dating back at least as far as the Cretaceous period. The 

 Australian Lung-fish {Epiceratodus) is found to-day only in 

 portions of the Burnett and Mary Rivers of northern Queens- 

 land, and the other members of this ancient tribe occur in 

 tropical Africa and South America (Fig. 99). The second is a 

 species of Osteoglossid found in northern Australia and New 

 Guinea, which belongs to a genus {Scleropages) containing one 

 other species found in Sumatra and Borneo. The Osteoglossids 

 are a very ancient family, of which the remaining existing 

 members occur in Africa and South America (Fig. 100). The 

 almost complete absence of fishes of the order Ostariophysi is 

 remarkable, and a comparison of the fauna of Borneo on the 

 one hand with the neighbouring island of Celebes on the other 

 produces striking results: in the former there are hundreds of 

 species of Cyprinids, Loaches, Suckers, Cat-fishes, Labyrinthic- 

 fishes, etc., peculiar to the island or common to the Malay 

 Peninsula and Archipelago as far as Wallace's Line, whereas, 



