Perisodactyl or Perissodactyl: How To spell?
The word Perisodactyl is misspelled against Perissodactyl, a noun meaning "One of the Perissodactyla."
Perissodactyl has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings peri & odactyl which should not be misspelled with single 'S'
Wrong Spelling:  peri-s-odactyl  Correct Spelling:  peri-ss-odactyl 
Find more incorrect spellings of Perissodactyl to spell right way.