528 PARENTAL CARE AMONG FRESH-WATER FISHES. 



with age. At first there are, as tlie basis, exceedinoly thin bony lam- 

 inae, wliich increase in number and plication with time, till finally 

 they well merit the designation of labyrinthiform, if not " labyrin- 

 thiform branchiae," which was conferred on them by Cnvier. The 

 osseons himinse are covered with a special mncons and aeriferous tis- 

 sue and functions as a lung. It is by means of this organ that the 

 fish is enabled to avail itself of a supply of air which it seeks or is 

 forced to avail itself by stress of circumstances. 



Although occurring in " tropical Asia and Africa," the Anaban- 

 toideans are by no means found everywhere in those countries, and 

 their distribution indeed is remarkable. The Anabantids are more 

 widely distributed in Africa than in Asia, but while the Osphrome- 

 nids have a wide range in southern Asia and the archipelagoes, they 

 are limited (so far as known) to a single genus and species {Micra- 

 cdiitJnifi marchii) , restricted to tributaries of a single river of western 

 Africa — the Ogowe. Consequently, a vast area exists between the 

 present headquarters of the family and the area where a single relict 

 survives to bear testimony to the former extension of the family. 

 Why fishes apparently so well fitted for the struggle of life should 

 have succumbed is one of the many mysteries which constantly con- 

 front the naturalist. 



Only one of the Anabantoidean families — the Osphromenids — -re- 

 quires notice here. Its members construct remarkable nests. 



THE OSPHROMENIDS. 



The Gourami family have an oblong and rather irregular body, 

 covered with scales which extend over the head; the head and mouth 

 small, the palate toothless, and the fins very diverse. Almost every 

 genus is distinguished by special fin modifications, but the anal always 

 extends farther backward than the dorsal. The ventrals are more or 

 less behind the roots of the pectorals and have a spine (in one genus 

 atrophied) and an outermost more or less elongated ray developed at 

 some expense to the others — that is, the others are reduced in length 

 or more or less suppressed. 



There is an extraordinary rajige of variation in the dorsal and anal 

 as well as ventral fins. At one extreme are the Gourami and its near 

 relatives, whose fins are very long and have munerous spines, and at 

 the other the pla-kat or fighting fish {Bctta jyiignax)^ deprived of 

 both dorsal and anal spines. Again, at one extreme are the Poly- 

 acavthi^ with the completely developed ventrals (having a spine and 

 five rays) of an ordinary acanthopterygian fish, and at the othei' the 

 Trirhogasters^ with those fins each represented by a single filamentous 

 ray. Between such extremes are a number of intermecHate forms, 

 which certify to the fact that such differences do not have the value 



