Final /-s/ does not exist in modern T???in; however, *-s in Proto-T???in can be reconstructed. The distinction between *-s and *-h in Proto-T???in phonology is suggested by two types of final correspondences, i.e., *-s has become /-yh/ in Mal but /-t/ in Pray, and *-h has been kept as /-h/ in both Mal and Pray. This fact was pointed out by Filbeck in 1978; however, no Proto-T??? in forms were reconstructed by him. 

To show a clearer picture of the phonological history of T???in, 68 Proto-T???in forms were reconstructed, 17 with final *-s and 51 with final *-h. The 68 Proto-T???in reconstructed lexical items, (1)-(17) and (34)-(84), including 16 Proto-Mal reconstructed forms having *-s, (18)-(33), are presented in this paper with Thai and English glosses. Khmu??? and Mlabri cognates from the author???s corpus are also provided.