On The Morphological Feature of The Gill of Amphibious and Air Breathing Fishes

Three air-breathers, two amphibious fishes, two sluggish water-breathers and five active or intermediately active water-breathers were compared for the gill structure, and the following results were obtained so far as the used data of these species are concerned . 1) In the ratio of the gill area to body surface area , air-breathing and amphibious fish < sluggish fish < water-breather. 2) In the total number of filaments, amphibious fish≒sluggish fish < air-breather < water-breather. 3) In the density of secondary lamella, sluggish fish < air-breather < water-breather. 4) As the ratio of the fourth to the first gill arch , in the length of secondary lamella and the filaments, air-breather < amphibious fish < water-breather. 5) In the total length of filaments and the area of secondary lamella , air-breathing and amphibious fish < sluggish fish. 6) There are environmental and respiratory differences among amphibious fishes and air-breathers , and consequently, the differences of gill structure, especially in the fourth gill arch , are indicated.