class Merostomata vs Merostomata

class Merostomata and Merostomata both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Merostomata	Yes	No	No	No
Merostomata	Yes	No	No	No

As nouns, class Merostomata and Merostomata are synonyms defined as:

class Merostomata and Merostomata: used in some classifications; includes the orders Xiphosura and Eurypterida

class Merostomata (noun)	Merostomata (noun)
used in some classifications; includes the orders Xiphosura and Eurypterida	used in some classifications; includes the orders Xiphosura and Eurypterida