I don't think a taxonomic order can be used in the plural (but please fix it if I'm wrong).
I believe species names are lower case and higher taxonomic levels are upper case so I made it Cetacea. (And just realized it the entry should still be lower case but the example below known should be upper case). Also please fix if I'm wrong about usage, that may only apply to binomial names. JillianE 03:02, 19 December 2005 (UTC)