PEKCID^. 385 



About ten species are known, inhabiting fresh waters of 

 the coasts of the Indo-Pacific, and being especially common 

 in the islands of this region, and also in Tropical Australia. 

 Some live also in brackish water. Though of small size they 

 are esteemed as food. 



Therapon. — Body oblong, compressed, with scales of moderate 

 size. All the teeth are villiform, those of the vomer and pala- 

 tine bones being rudimentary, and frequently absent. One dorsal, 

 with a depression in its upper margin, and twelve or thirteen 

 spines ; anal fin with three. Prseoperculum serrated. Air- 

 bladder with two divisions, an anterior and posterior. Six 

 branchiostegals. 



About twenty species are known, the distribution of which 

 nearly coincides with Dides, but as some of the species are 

 more or less marine, the genus is spread over the whole area 

 of the tropical Indo-Pacific. Other species, especially those 

 of Australian rivers, are entirely limited to fresh water. TJi. 

 theraps, Th. scrvus, and Th. cuvicri belong to the most com- 

 mon fishes of that area, extending from tlie east coast of 

 Africa to Polynesia. They are readily recognised by the 

 blackish longitudinal bands with which the body is orna- 

 mented. All the species are of small size. Helotes is closely 

 allied to this genus. 



Pristipoma. — Body oblong, compressed, with ctenoid scales of 

 moderate size. Cleft of the mouth hori- 

 zontal, not very wide, with the jaws nearly 

 equal in length anteriorly; a central pit 

 below the chin ; villiform teeth in the 

 jaws without canines ; palate toothless. 

 One dorsal, with eleven to fourteen spines ; 

 anal with three. Vertical fins not scaly, or 

 with scales along the base only. Prajoper- ^'^- 155.— Lower view of 



, , 1 -r. 1 • , 1 mandible of Pristipoma 



culum serrated. Branchiostegals, seven. manadense 



About forty species are known, all from the sea. They 

 are extremely common between the tropics, some of the 



2 c 



