(Latin plural genera), 1550s as a term of logic, "kind or class of things" (biological sense dates from c. 1600), from Latin genus (genitive generis) "race, stock, kind; family, birth, descent, origin" (from suffixed form of PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups).
"cartilaginous fish resembling or related to a shark of the genus selachii," 1835; the genus name from Latinized form of Greek selakhos (plural selakhē) "cartilaginous fish," which is of uncertain origin.
genus of fungi, Modern Latin, from Greek pilos "felt" (see pileated) + bōlos "a clod, clump."
"Australian duck-mole," 1799, from Modern Latin, from Greek platypous, literally "flat-footed," from platys "broad, flat" (from PIE root *plat- "to spread") + pous "foot," from PIE root *ped- "foot." Originally the genus name, but entomologists had given it earlier to a genus of beetles; it was retained for the species after the genus name was changed in 1800 to Ornithorhyncus. OED has Australian platypussary (1945) "enclosure in which platypuses are kept."