1468 , 
Genus Heteronycterus Kaup 
Heteromycteru s Kaup , Archiv Naturges., vol, 24, pt. 1, p. 103, 1858, 
(Type Heter o mycterus capen eis Kaup , monotypic.) 
Arcat® Jordan and Starks , Proc. U, 3, Nat, Mus., vol. 31, p. 226, 1306. 
(Type Achirus japonicus Schied el, orthotypic.) 
Monodichthys Chabanaud , Bull. Mus. Hist. Nat. Paris, 1925, p. 356. 
(Type, Monodichthys probosciaeus Chab anaud, monotypic,) 
Snout prolonged into hook. Anterior nostril of blind side 
dilated and fringed. Inter-branchial septum perforated. Dorsal rays 
extend to end of snout. Ventrals markedly asymmetrical, on right side 
I 
median* elongate and joined to anal# 
