Genus Rhina Bloch & Schneider, 1801

Type species. Rhina ancylostomus Bloch & Schneider, 1801 (designated by indication under ICZN Opinion 6).

Description. Nostrils large, very elongate and well separated, length subequal to internasal distance; posterior aperture slightly oblique, almost entirely covered by anterior nasal flap, exposed part much smaller than anterior aperture. Anterior nasal flaps bilobed, moderately developed but not fused to form a nasal curtain, long based (exceeding 2/3 of nostril length), posterior lobe inserted on snout at nostril margin adjacent innermost corner of posterior aperture (flaps widely separated, but barely more than internasal distance); anterior aperture relatively large, subtriangular, expanded horizontally, its posteromedial edge formed by broadly rounded, outer lobe-like extension of anterior nasal flap (lobe positioned anteriorly on flap); inner lobe of anterior nasal flap long, narrow with an oblique, convex margin; posterior margin of anterior aperture bordered by slender, long-based posterolateral nasal flap; posterolateral nasal flap extending posteromedially well into posterior aperture as broad free extension (reaching beyond middle of posterior aperture of nostril); posterior nasal and posterolateral nasal flaps semi-continuous nostril posterior margin; base of latter relatively long (slightly exceeding half of nostril width). Lower jaw very strongly tri-convex; skin margin forming upper lip strongly concave; usually four short but prominent, posterolaterally directed grooves at its angle; oral groove absent, several weak transverse grooves on chin.

Species. R. ancylostoma Bloch & Schneider, 1801 .