The word "orthonotus" is spelled with the "or-tho-no-tus" sounds in IPA phonetic transcription. The initial "or" sound is pronounced with the vowel sound in "more," while "tho" is pronounced with the "th" sound in "think" and the vowel sound in "lot." The "no" sound is pronounced with the vowel sound in "not," and "tus" uses the "t" sound and the vowel sound in "bus." Recall these sounds in sequence to decode and properly pronounce "orthonotus."
In geol., a sub-genus of fossil bivalves, so called from their long, straight, plaited backs.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.