In binomial nomenclature, the correct way to write a species name is using a two-part format: the first part denotes the genus and is capitalized, while the second part denotes the species and is written in lowercase. Both parts should be italicized or underlined if handwritten.
For example, Homo sapiens is written correctly, with "Homo" (the genus) capitalized and "sapiens" (the species) in lowercase.
If you have specific species names in mind, please provide them, and I can confirm which is written correctly according to binomial nomenclature rules.