Order HETEROMI Gill (Boulenger emend.). 



Airbladder without an open duct. Body elongate, tail tapering 

 to a point in recent forms. Scales cycloid; lateral line present. 

 Orbito-rostral part of cranium elongate. Parietals meeting in 

 the middle line, excluding the frontals from the supraoccipital. 

 Pectoral arch suspended from supraoccipital or epiotic. Meso- 

 coracoid arch absent, scapula lamellar. Opercle well developed. 

 Fins with or without spines. Pectorals inserted high up the 

 sides. Ventrals abdominal and not attached to cleithra. Anal 

 very long, reaching end of tail; a caudal rudimentary or wanting. 

 Anus posterior. Anterior vertebrae not modified. Mouth generally 

 small, inferior, bordered by maxillaries and intermaxillaries 

 or by the lastnamed only. 



Embracing the recent Halosauridae, Lipogenyidae and Nota- 

 canthidac of which the first family only is represented in the 

 indo-australian Archipelago. 



I. Fam. Halosauridae. 



Elongate, somewhat compressed, with the abdomen rounded; 

 tail very long and strongly compressed, tapering into a filament, 

 without caudal. Head conical, the facial bones with large 

 muciferous cavities. The flattened snout projecting beyond the 

 mouth, which is inferior, of moderate width and anteriorly 

 bordered mesially by the intermaxillaries, laterally by the 

 maxillaries. No barbels. Teeth small, in villiform bands on the 

 jaws, on the rudimentary pterygoids and palatines, none on vomer 

 or tongue. Scales rather small, cycloid, very deciduous; head, 

 at least on cheeks, temples and on upper part of opercle 

 scaly. Lateral line running along lower profile; its scales scarcely 

 enlarged and destitute of luminous organs, or these organs are 



iNnO-AUSTRALIAN FISHES IV. I 



