What part of a scientific name is the species?

A scientific name of an organism contains two parts. The first name is the genus name and the second name is the species name. There are some simple rules in writing a scientific name:

a). The first letter of the Genus name must be capitalized.

b). The first letter of the species name is not capitalized.

c). Both names must be underlined or italicized.

I believe that would make the Genus the most important part of the scientific name of an organism.