'X' and 'Y' are the components of binomial nomenclature. This naming system was proposed by 'Z' :

	X	Y	Z
1.	Generic name	Specific epithet	Carolus Linnaeus
2.	Specific epithet	Generic name	R.H. Whittaker
3.	Specific epithet	Generic name	Carolus Linnaeus
4.	Generic name	Specific epithet	R.H. Whittaker

X - Generic name, Y - Specific epithet, Z - Carolus Linnaeus

In the binomial nomenclature system, which is used for naming species, the generic name (X) comes first, followed by the specific epithet (Y). This naming system was proposed by Carolus Linnaeus. 

R.H. Whittaker proposed the Five Kingdom Classification system. This classification system categorises living organisms into five kingdoms, based on their characteristics. The five kingdoms proposed by Whittaker are Kingdom Monera, Kingdom Protista, Kingdom Fungi, Kingdom Plantae and Kingdom Animalia.