INTRODUCTION. 



The present volume is the fourth of the series of volumes 

 devoted to the knowledge of the fishes of the indo-australian 

 Archipelago and the third in which we endeavour to give a 

 concise description of all the fishes at present known to inhabit 

 the seas and freshwater of that Archipelago and also to show 

 their distribution through this area. We have already defined 

 the character and geographical limits of this area in the 

 Introduction to the second volume. 



In the present volume the orders of Heterouii, Solenichthyes, 

 Synentognathi, Percesoces, Labyrinthici and Microcyprini are 

 treated. 



The material at our disposal has already been mentioned 

 in the Introduction to the former volumes, so that we have 

 only to add the following new additions. 



In acknowledging our obligations to contributors of valuable 

 material, we have to mention the following collections: 



From Sumatra a collection made by Jonkheer F. C. VAN 

 Heurn at Deli. 



From New Guinea an extensive collection made by Jonkheer 

 W. C. VAN Heurn in the Mamberamo-river and its tributaries. 



In former volumes we had the opportunity to thank Dr. J. 

 C. Koningsberoer for his interest and collaboration in the 

 present work which was published with his aid. 



Dr. W. M. DOCTERS VAN Leeuwen, his successor as Director 

 of 's Lands Plantentuin at Buitenzorg, Java, has shown the 



