302 



2. Nape with a broad black cross band 

 broadly edged with white in front and 

 behind. Pectorals more than twice to 



four times in head. Snout prominent. O. cephalozona p. 303. 



3. Coloration uniform. Pectorals more than 



thrice in head. Snout prominent. . . . O. bernsteini p. 304. 



b. Head and trunk 1.5 1.6 in tail. 



1. Vomerine teeth in a double series. 



Head about 2^/. 2 times in trunk. . . . O. apicalis p. 305. 



2. Vomerine teeth in a triple series 

 anteriorly. Head nearly four times in 



trunk 0. singapurensis p. 306. 



c. Head and body more or less than twice 

 in tail. Vomerine teeth more or less irre- 

 gularly biserial. Head about four times 



in trunk O. macrochir p. 306. 



B. Origin of dorsal above gillopenings. 



a. Head and trunk longer than tail. Pectorals 



5'/2 times in head O. polyophthalmus p. 307. 



b. Head and trunk shorter than tail. Pectorals 

 2^2 times in head. 



1. Teeth uniserial in jaws and vomerjon 



intermaxillary plate 5 stouter teeth 



arranged in a A 0. melanochir p. 308. 



2. Teeth uniserial in jaws and vomer; 



only anteriorly in the mandibles they 

 are irregularly triseriate and stouter as 

 also the 6 serially arranged pairs on 



the intermaxillary plate 0. altipinnis p. 308. 



II. Maxillary teeth in a double series, the inner 

 of which may be incomplete. 

 A. Mandibulary teeth in a double series. 

 a. Head and trunk about twice in tail. 

 i. Vomerine teeth in 2 series. 



a. Head 5 3 / 5 times in trunk O. rhytidoderma p. 309. 



b. Head 4 4^2 times in trunk. 



a. Height 46. Teeth in the maxil- 

 laries biserial, except the fore- 

 most 0. rhytidodermatoides p. 309. 



& Height about 68. Teeth in the 

 maxillaries only biserial in the 

 middle O. lumbricoides p. 310. 



