I. Fam. HOMALOPTERIDAE. 



Head and anterior part of body depressed, lower surface 

 flattish. Pectorals and ventrals horizontally inserted, generally 

 several of their outer and sometimes of their inner rays simple. 

 No movable spine before or below eye. Dorsal and anal fins 

 short, the former opposite to ventrals. Mouth inferior, its upper 

 border formed by intermaxillaries only. At least three pairs 

 of barbels, which may be nasal, rostral or maxillary barbels. 

 Scales small, cycloid. Lateral line present. Gillopenings narrow. 

 Gillmembranes united with isthmus. No pseudobranchiae. 

 Pharyngeal teeth in a single series, eight to numerous in number. 

 Airbladder reduced, divided into two lateral portions, each 

 enclosed in a bony capsule. 



Distribution: Southern Asia, in fresh water. 



Key to the indo-australian genera. 



1. Ventrals with 18 21 rays, united to form a sucto- 

 rial disk Gastromyzon p. 2. 



2. Ventrals separated, with 8 n rays. 



a. Five pairs of barbels, one nasal pair Glaniopsis p. 5. 



b. Three to four pairs of barbels, no nasal ones. 



a. Three pairs of barbels, two of which in front 



of snout Homaloptera p. 6. 



/3. Four pairs of barbels, three pairs of which in 



a horse-shoe shaped groove before mouth. . . Parhomaloptera p. 20. 



i. Gastromyzon Gunther. 



(GiJNTHER, Ann. Mag. Nat. Hist. (4) XIV. 1874, p. 454). 



(Lcpidoglanis Vaillant, Neogastromyzon Popta). 



; Head and anterior part of body ventrally flattened. Head 

 and snout b'road, rounded, eye superior, with a free orbital 

 aia'fgin.. Anterior and -posterior nostrils separated by a cutaneous 

 flap. Mouth inferior, transverse, slightly curved; at its corner 

 a more or less rudimentary barbel, 4 others before the mouth. 

 Pectorals with a long base beginning vertically below eye; 

 ventrals with a long curved base, united posteriorly; between 

 base of pectorals and ventrals a lateral extension of the abdo- 

 minal skin (Fig. la). By this arrangement the whole flattened 

 abdominal surface, together with the fins and the flattened 



