245 
*/, length of eye. Lighter or darker brown, underside of head 
and belly whitish, some specimens with irregular dark markings. 
Length over 180 mm. 
Nomen indig.: Sinonga. 
Habitat: North New Guinea (Lake Sentani!). 
4. Fam. CHACIDAE. 
Head very large, strongly depressed, nearly aequilateral. 
Body depressed anteriorly, compressed posteriorly and rapidly 
tapering. Lower jaw prominent. Mouth very wide. The tubular 
anterior nostrils on its anterior border; posterior nostrils at 
some distance behind, with a short tentacle. Eyes very small, 
covered by skin. A barbel at the corner of the mouth, origi- 
nating from a broad fold of the skin, two mental ones behind 
the border of the mandible, distant from each other; at some 
distance behind them a pair of mandibulary barbels. Moreover 
the skin is provided with arborescent prominent papillae. 
Lateral line represented by a papillated and tuberculated 
ridge reaching the tail. The short dorsal fin with a strong 
spine and three or four rays. Anal with 7—10 rays. Rounded 
caudal with a long procurrent dorsal part and a shorter ventral 
part. Ventrals very broad, behind the dorsal, six-rayed. Pectorals 
with four or five rays, with a short, very strong spine, the 
broad anterior inferior border of which is concave. Gillmem- 
branes confluent with the skin of the broad isthmus, the gill- 
opening being thereby reduced in extent. Small villiform teeth 
in jaws. Palate edentulous. No axillary pore. 
1. Chaca Valenciennes. 
(VALENCIENNES in: Bélanger, Voyage Indes orientales, Zool. Poissons, 1834, p. 385). 
For characters of the single genus see those of the family. 
Fig. 99. Chaca chaca (Ham. Buch.). 
