The voiceless sibilant sound [s] usually survived from Primitive Elvish into Ilkorin (PE19/19, 23), though primitive initial [s] vanished before most consonants, frequently unvoicing or spirantalizing the following consonant in the process.
References ✧ PE19/19, 21, 23
|Ilk. [no change]||
||✧ PE19/19 (s- > s-); PE19/23 (-s- > -s-)|
||✧ PE19/21 (sj- > s)|