slender, cigar-shaped shark with two very small spineless,
roughly subequal dorsal fins set posteriorly and close
together; no anal fin; ventral lobe of caudal fin noticeably
well-developed and almost subequal to dorsal lobe. Low
keels on caudal peduncle. Snout short, bulbous and broadly
conical; eyes fairly large; spiracles prominent. Lips
fleshy and expanded; lower-jaw teeth conspicuously large,
triangular-cusped, in 25 to 31 rows; upper teeth small.
Gill-slits very small. Pectoral fins small. Colour dark
brown or dark tan dorsally, lighter ventrally; a distinctive
collar of darker pigment encircling the anterior body
at the level of the gills. Posterior margins of all
fins lighter and rather transluscent.