514 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



16&. No enlarged unpaired scale in median line on top of 

 head anteriorly. 

 17a. Head compressed or cylindrical. 

 IScf. Opercle and preopercle more or less covered 

 with large scales, scaled only on upper part, 

 or scaleless ; head compressed ; gill openings 

 restricted ; scales on top of head not extend- 

 ing between eyes ; some teeth enlarged. 

 Ida. Scales in longitudinal series 25 to 45; teeth 

 in outer and inner rows of both jaws en- 

 larged and caninoid ; teeth in outer row of 

 lower jaw extending only half length of 

 jaw, the last teeth recui-ved canines ; tongue 

 truncate to bilobate; branched dorsal and 



anal rays 6 to 12 Acentrogobius 



19&. Scales in longitudinal series 50 to 75; teeth 

 in outer row of both jaws enlarged, those 

 in outer row of lower jaw extending only 

 half length of jaw, the last teeth recurved 

 canines ; tongue rounded or truncate ; 

 branched dorsal and anal rays 12 to 16. 



Amblygobius 

 18&. Opercle, preopercle, and cheek fully covered 

 with large scales, which may be in regular 

 horizontal rows separated by longitudinal 

 grooves ; scales in longitudinal series 24 to 

 32 ; outer row of teeth in each jaw enlarged, 

 last teeth in outer row of lower jaw may be 

 canine, or caninoid. 

 20a. Head compressed ; interorbital space narrow, 

 0.5 diameter of eye or less ; scales on top of 

 head extending to eyes or very slightly into 

 interorbital space; scales on cheek and pre- 

 opercle forming an unbroken covering or 

 divided by a horizontal groove- Gnatholepis 

 20&. Head cylindrical; interorbital space wide, 

 more than diameter of eye; scales on top 

 of head extending on interorbital space 

 nearly to line from anterior margin of eyes ; 

 scales on cheek and preopercle in about 6 

 horizontal bands divided by 4 horizontal 



grooves Aulopareia 



18c. Opercle, preopercle, and cheek naked; scales on 

 body ctenoid, confined to posterior part, and 

 22 to 30 in longitudinal series ; teeth in upi)er 

 jaw with outer row enlarged, in lower jaw 

 with inner row enlarged, no canines. 



Zonog'obius 

 17fi. Head depressed. 

 21a. Opercle more or less covered with large scales, 

 preopercle and cheek naked ; scales in longi- 

 tudinal series 23 to 40; no teeth noticeably 

 enlarged; tongue truncate or slightly emar- 

 ginate Vaimosa 



