Thalasinian or Thalassinian: How To spell?
The word Thalasinian is misspelled against Thalassinian, a noun meaning "Any species of Thalaassinidae, a family of burrowing macrurous Crustacea, having a long and soft abdomen."
Thalassinian has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings thala & inian which should not be misspelled with single 'S'
Wrong Spelling:  thala-s-inian  Correct Spelling:  thala-ss-inian 
Find more wrongly spelled words of Thalassinian to spell it well.