Prothalia or Prothallia: How To spell?
The word Prothalia is misspelled against Prothallia, which is plural of "Prothallium"
Prothallia has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings protha & ia which should not be misspelled with single 'L'
Wrong Spelling:  protha-l-ia  Correct Spelling:  protha-ll-ia 
Find more incorrect spellings of Prothallia to spell right way.