c. The abl.-gen. sing. changes ṛ to ur (or us: 169 b).
d. The gen. pl. (as in i and u-stems) inserts n before ām, and lengthens the stem-final before it. But the ṛ of nṛ́ may also remain short.
e. The above are the rules of the later language. The older presents certain deviations from them. Thus:
f. The ending in nom.-acc.-voc. du. is (as universally in the Veda) regularly ā instead of āu (only ten āu-forms in RV.).
g. The i of loc. sing. is lengthened to ī in a few words: thus, kartárī.
h. In the gen. pl., the RV. has once svásrām, without inserted n; and narā́m instead of nṛṇā́m is frequent.
i. Other irregularities of nṛ́ are the sing. dat. náre, gen. náras, and loc. nári. The Veda writes always nṛṇā́m in gen. pl., but its ṛ is in a majority of cases metrically long.
j. The stem usṛ́ f. dawn has the voc. sing. uṣar, the gen. sing. usrás; and the accus. pl. also usrás, and loc. sing. usrā́m (which is metrically trisyllable: usṛā́m), as if in analogy with ī and ū-stems. Once occurs usrí in loc. sing., but it is to be read as if the regular trisyllable form, uṣúri (for the exchange of s and ṣ, see 181 a).
k. From stṛ́ come only tā́ras (apparently) and stṛ́bhis.
l. In the gen.-loc. du., the r is almost always to be read as a separate syllable, ṛ, before the ending os: thus, pitṛós, etc. On the contrary, nánāndari is once to be read nánāndri.
m. For neuter forms, see below, 375.
372. Accent. The accentuation follows closely the rules for i- and u-stems: if on the final of the stem, it continues, as acute, on the corresponding syllable throughout, except in the gen. pl., where it may be (and in the Veda always is) thrown forward upon the ending; where, in the weakest cases, ṛ becomes r, the ending has the accent. The two monosyllabic stems, nṛ́ and stṛ́, do not show the monosyllabic accent: thus (besides the forms already given above), nṛ́bhis, nṛ́ṣu.
373. Examples of declension. As models of this mode of inflection, we may take from the first case (with आर् ār in the strong forms) the stems दातृ dātṛ́ m. giver and स्वसृ svásṛ f. sister; from the second class (with अर् ar in the strong forms), the stem पितृ pitṛ́ m. father.