3^9 



head 5, its breadth i' 2 / 5 in its length, its dorsal profile slightly 

 convex, slowly sloping down to the snout, which is bluntly 

 conical. Its lower border runs in a somewhat oblique and posterior 

 direction to the upperlip, which borders in a semicircle the quite 

 inferior mouth. A vertical through the mouth is nearer to the 

 eye than to the point of the snout, it is only about J / 5 of the 

 length of the head. The somewhat swollen lips are connected by 

 a rather broad fold. Nostrils close together, situated below a 

 horizontal connecting eye and point of snout. Crownshield 

 with undulating rugae, radiating from a central point. Occipital 

 process keeled, '/ 2 longer than broad at its base, its rectilinear 

 sideborders converging, its truncate hindborder somewhat 

 emarginated and touching the rugous, crescentic basal bone 



F'g* '39- Tetranesodon conorhynchus M. Web. 



of the dorsal spine. Before the crownshield a narrow, oval 

 fontanel about as long as snout. Humeral process rugous, 

 elongate and truncate. Eye lateral, situated in the anterior 

 half of head, 6 2 / s in head, twice in snout and 2 ] / 2 times in 

 the very convex interorbital space. Maxillary barbels 2 ! / 2 

 times in head, reaching nearly halfway to posterior border of 

 opercle, mandibulary barbels ! / 3 longer than eye, mental barbels 

 slightly shorter. Mandibulary and mental barbels originating 

 close together in one line. Height of dorsal equal to head 

 from posterior nostril, its spine slightly shorter, flattened, 

 anteriorly with weak, posteriorly with stronger serrations. Base 

 of adipose fin longer than dorsal, its distance from dorsal ! /2 ^ ts 



