Mareus or Mareis: How To spell?

The word Mareus is misspelled against Mareis, a noun meaning "A Marsh."

Word contains consecutive vowels 'EI' in between alphabets mar & s is misspelled as 'EU'
Wrong Spelling:  mar-eu-s 
Correct Spelling:  mar-ei-s 
Check more misspelled words of Mareis to spell it correct.