The correct form for writing names of organisms in the binomial nomenclature is
Genus species.
Like, for example in the name of the frog
Rana esculenta, where Rana is the genus.
The binomial nomenclature was developed by a famous Swedish biologist Karl Linnaeus. The term binomial means that every species' name is made from the name of its genus and another word specifying a trait of the species.
It's important to mention that all Latin names of organisms should be written in italics.
