The genus name Nebrius is derived from the Greek word nebris or nebridos , meaning the skin of a fawn . The specific epithet ferrugineus is Latin for " rust @-@ colored " . Other common names for this species include giant sleepy shark , Madame X ( a name coined by the shark fisherman Norman Caldwell in the 1930s for the then @-@ unidentified Australian specimens ) , nurse shark , rusty catshark , rusty shark , sleepy shark , spitting shark , and tawny shark . Based on morphological similarities , Nebrius is believed to be the sister genus of Ginglymostoma , with both being placed in a clade that also contain the short @-@ tail nurse shark ( Pseudoginglymostoma brevicaudatum ) , the whale shark ( Rhincodon typus ) , and the zebra shark ( Stegostoma fasciatum ) .