204 
ring outward. On the vomer few bluntly rounded teeth in 
two roundish groups, their own diameter apart, which distance 
increases when the groups are smaller. Similar teeth in two 
longish, oval groups on the palatines, nearly touching the 
vomerine groups. A median longitudinal keel on the palate. 
10 stiff gillrakers, flattened at their base and separated by a 
broad, rather high membrane from about 13 stiff but low 
processes along the hindborder of the gillarch. Dark brown 
above, white below. Dorsal, adipose fin, caudal, distal part of 
anal and pectorals and basal part of ventrals dark, anal and 
ventrals sometimes hyaline. Length 425 mm. 
Habitat: South New Guinea (Lorentz river!). 
In fresh water. 
14. Arius nudidens M. Web. 
Arius nudidens Max Weber, Nova Guinea IX, livr. 4. 1913, p. 538. 
B. Q; ID ee Tas ia IQ; Py 1 tae. Wiese: 
Elongate; height under dorsal spine 5°*/,—6, head more 
than 3, its width 1°/,—1*/, in its length. In adults the dorsal 
profile gently sloping down in a straight line to the broad, 
flat, rounded snout, which goes 2'/, times or somewhat more in 
the head and projects so much before the lower jaw that the broad 
band of teeth in the upper jaw is completely exposed. Gape 
rounded, more than 2 times in head; lips strongly thickened 
at corner of mouth. Headshields corrugate, occipital process 
about 1'/, times longer than broad at base, sharply keeled 
in young ones, less so in adults, its sideborders convergent, 
rounded behind and touching the crescentic basal bone of 
dorsal spine. Median fontanel short and shallow. Rough humeral 
process short but broad. Eye with incomplete orbital ring, 
directed somewhat upwards, 9'/,—11*/, in length of head, 
2'/,—4'/, in the slightly convex interorbital space. Maxillary 
barbels extending to base of pectorals, mandibulary ones on pec- 
torals, mental ones about a half shorter. All barbels are ribbon- 
shaped, less so in young ones, where they are relatively 
shorter. Height of dorsal equal to head without snout, its 
flattened spine with serrated front and hindborders equal to 
postorbital part of head, one eye-diameter longer in young 
specimens. Base of well developed adipose fin much longer 
than that of dorsal, about 2 times in its distance from last- 
named. Anal with the hindborder concave, its greatest height 
oqus\ 2 
