337. Declension II - Dual

 Dual. a. The later and earlier language agree in making the nom.-acc.-voc. masc. and fem. by lengthening the final of the stem. The same cases in the neuter (according to the rules given above) end later in inī and unī; but these endings are nearly unknown in the Veda (as, indeed, the cases are of only rare occurrence): AV. has inī twice (RV. perhaps once); VS. has unī once; RV. has  from one u-stem, and ī, once shortened to i, from one or two i-stems.

b. The unvarying ending of instr.-dat.-abl., in all genders, is bhyām added to the unchanged stem.

c. The gen.-loc. of all ages add os to the stem in masc. and fem.; in the neut., the later language interposes, as elsewhere in the weakest cases, a n; probably in the earlier Vedic the form would be like that of the other genders; but the only occurrence noted is one unos in AV.