_Canis lupus_
Here's why:
* Italics: Scientific names are always written in italics.
* Genus and Species: The name consists of two parts: the genus ( _Canis_ ) and the species ( _lupus_ ).
* Capitalization: The genus name is capitalized, while the species name is not.
You can also abbreviate the genus name after it has been written out in full once:
_C. lupus_