Cycloidey or Cycloidei: How To spell?

The word Cycloidey is misspelled against Cycloidei, a noun meaning "An order of fishes, formerly proposed by Agassiz, for those with thin, smooth scales, destitute of marginal spines, as the herring and salmon. The group is now regarded as artificial."

Word ends with consecutive vowels 'EI' preceded by alphabets 'cycloid' is misspelled as 'EY'
Wrong Spelling:  cycloid-ey 
Correct Spelling:  cycloid-ei 
Find more incorrect spellings of Cycloidei to spell right way.