27a.  (From 26b.) Mouth inferior, barbel present; no dark markings present at base of caudal fin, i.e., spot or chevron, and no lateral stripe.
Genus Hybopsis

27b. (From 26b.) Mouth superior and oblique, terminal, subterminal, or possibly appearing inferior; if mouth inferior then dark markings at base of caudal fin (i.e., spot or chevron) and lateral stripe will be present; barbel usually absent.
Genus Notropis