GOBIIDAE Psammogobius biocellatus, 5.3 cm SL (photo by Seishi Kimura) Psammogobius biocellatus, 6.0 cm SL (photo by Ukkrit Satapoomin) Psammogobius biocellatus (Valenciennes, 1837) Sleepy Goby D VI+I, 9; A I, 8-9; P1 18; LR 29-30; PDS 14-15. Body moderately elongate and subcylindrical, compressed. Head depressed; lower jaw well protruding beyond upper jaw; tongue bilobate; small lappet over iris; gill opening extending well anteriorly to a vertical through preopercular margin; gill membranes united medially, with free posterior margin across isthmus. Pelvic fins united medially; frenum present. Scales ctenoid, excepting those on belly and pectoral base cycloid. Sensory canals and pores present on head; longitudinal pattern of sensory-papillae rows on cheek; aggregation of sensory papillae just behind chin. Color: head and body blackish or grayish brown with indistinct black mottles and lines. Size: 12.0 cm TL. Distribution: Indo- Pacific. Remarks: found in tidal estuaries, especially common in mangrove creeks with sandy-mud bottoms.