The Spine-finned Teleostei 385 



two species inhabit the rivers of Borneo, Sumatra, and 

 Java. Similarly three species of CynogJossiis are fresh- 

 water, one or two others inhabit the Gangetic and other 

 deltas, while the remaining 24 are marine. All indications 

 at present are that the fluviatile species are derivative from 

 the marine, and this is one of the decidedly rare instances 

 in which adaptation from a marine to a freshwater environ- 

 ment has been fairly well effected. 



The remaining marine families of Acanthopterygli indi- 

 cate derivation from some one of the freshwater groups 

 above studied. And this has occurred either by direct de- 

 scent, or proximately from one that had become marine. 



The small family Lobotidae would be extremely difficult 

 of explanation were It not for the existence of the genus 

 KiihJia (p. 378) of the Centrarchidae, as well as many 

 parallel cases that receive, as we believe, like explanations 

 with it. The family consists of Datn'wides that includes 

 two species, occurring In the rivers of the Malay Archi- 

 pelago, and westward to Slam, Burmah, and the mouth of 

 the Ganges. Lobotes has one or possibly two species that 

 extend along the shores of the United States southward to 

 the Guiana coast, and that reappears from Ceylon eastward 

 to the Chinese sea, the Sunda and the Moluccas Islands. 

 If we regard both genera as derivative from the Centrar- 

 chidae — as has already been proposed (2:658) — then 

 while Lobotes was becoming a marine form and working 

 eastward along the former S. Atlantis and Gondwana shore- 

 lines, Datnioides continued as a river type through annect- 

 ant species that worked eastward along the S. Atlantis 

 continent, and then became distributed over the Eastern 

 Archipelago, as Is Kuhlia also still. But while Kuhlia has 

 left traces of its eastward progress in African rivers, and 

 even reached Australia, Datnioides has been obliterated In 

 Africa, and seems to have failed In reaching Australia. 



That the above explanation is alike feasible and prob- 

 ably exactly correct is perfectly demonstrated In such groups 

 as the Characinidae, the Mormyridae, the Osteoglossldae, 

 and the CIchlldae amongst others, except that these have 

 all become more abundant, have remained wholly in fresh- 

 water, and have suffered less serious organic denudation. 



