211 



Synopsis of the species. 



A. Posterior nostrils above and behind eye. 



1. Barbels not reaching to the eye. Head 4 4 / 5 , 



eye $ l /. 2 H. chaperi p. 211. 



2. Barbels reaching the eye. Head about 6, eye 



4*/3 5Y-2 H- heterorhynchus p. 211. 



3. Barbels reaching the opercle. Head 5 5 '/a, 



eye 7 8 H. moolcnburghi 212. 



B. Posterior nostrils above frontmargin of eye, barbels 



short, stiff, hooked H. scleronema 214. 



i. Hemisilurus chaperi (Vaill.). 



Diastatomycter chaperi Vaillant, Bull. Soc, Philom. Paris, (8). III. 1891, p. 182. 

 Bull. Soc. Zool. XVIII. 1893, p. 61. Nouv. Arch. Mus. Hist Nat. (3). 

 V. Paris, 1893, p. 70. 



A. 93; V. 9. 



Height 4 3 / 5 , head 4 4 / 5 , eye 5^, subcutaneous, its centre 

 situated slightly in advance of the middle of the head. Inter- 

 orbital space about 4 in head. Snout obtuse, slightly more 

 than 3 in head. Maxillary barbels flexible, not reaching the 

 eye, mandibulary barbels far distant from symphysis, minute. 

 Anal long, free from caudal. Ventrals short. Pectorals trian- 

 gular, their spine 3 / 5 of the length of the fin. Villiform teeth 

 in more or less curved bands in the jaws and in two small 

 distant patches on the vomer. Length of single specimen 

 known 485 mm. [After Vaillant. Not seen by us]. 



Habitat: Borneo (Knapei). 



In fresh water. 



2. Hemisilurus heterorhynchus (Blkr.). 



Wallago heterorhynchos Bleeker, Nat. Tijdschr. Ned. Indie V. 1853, p. 514. 

 Hemisilurus heterorrhynchus Bleeker, All. Ichth. II. 1862, p. 94. 

 Hemisihirus heterorhynchus Giinther, Cat. Brit. Mus. V. 1864, p. 54. 

 Hemisilurus heterorhynchus Vaillant, Notes Leyden Mus. XXIV. 1902, p. 50. 



B. 12; A. 90 94; P. I. l6 I/; V. 9. 



Height 4 ! / 2 5, head about 6, eye subcutaneous, 4 ! / 3 5'/ 2 > 

 situated in the anterior half of the head, more than I ! / 2 in 

 the convexity of the interorbital space. Snout rounded, slightly 

 prominent, 3 in head. Anterior nostrils short tubes, at the 



