542 



Marvels of the Universe 



Liliputian forests on the shells of many sea-snails ; on the walls of rock-pools ; on the upper valves 

 of oysters and scallops, and even on the back and legs of many of the Spider-crabs, as well as on 

 piers and piles and submerged timber in general. 



THE BOMMI FISH 



BY SIR HARRY JOHNSTON, G.C.M.G. 



BoMMi, of course, is only a local West African name, the title, at any rate, by which this " fish out 

 of water " is known in the coast region of Liberia. Englishmen in \A'est Africa also speak of it as 



the " Mud-skipper." It is neces- 

 sary, perhaps, to quote its unwieldy 

 scientific name — Periophthalmus — 

 by which it is known to scientific 

 men. It exists throughout the 

 tropical regions of the Old World 

 from westernmost Africa to the 

 shores of New Guinea. Appar- 

 ently, however, there is only one 

 species. 



The Bomnii Fish is a membei 

 of the Goby family of marine or 

 estuarine fishes, most of which are 

 remarkable in one way or another 

 for developing powers of walking 

 or jumping over the ground rather 

 than progressing through the water 

 by the use of their fins. The 

 Bommi Fish, indeed, is fast be- 

 coming a land animal. It resorts 

 to the water for breeding purposes, 

 but as soon as it is mature, its 

 one desire seems to be to leave the 

 water (though it always remains 

 in the proximit}' of that element) 

 and lie on the mud or sand, or 

 even ascend the trunks or branches 

 of mangrove-trees or pandanus. It 

 is said that it usually prefers to lie 

 with the extremity of its tail in 

 the water, and it is enabled in 

 some way to oxygenate its blood through its verj- vascular tail-fin, which in this way replaces the 

 giUs. But this hardl}' explains the ability of the Bommi Fish to remain for such a long time quite 

 away from the water on the trunk of a tree. 



Of course, this creature is not in any way on the original line of ascent which was followed by 

 pristine types of fish that gradually developed into amphibians and from amphibians into reptiles. 

 It is an entirely independent attempt (there are many parallel ones) on the part of modern fish to 

 adopt a land life. The fish ancestors of the reptiles, mammalia and birds developed fore-limbs 

 and hind-limbs from out of paired fore-fins and hind-fins, which had a very considerable interval 

 between them ; but nearly all modern fish, including the Bommi, allowed the interval between the 



THE BOMMI 



The Bommi has developed out of its 

 appendages some\vhat liUe ^vebbed fingers : 



FISH. 



fore-fins very serviceable arms and 

 while the hind-fins support the body 

 for leaping, and are provided with a kind of sucUer for the purpose of clinging. 



