Words ending in the feminine affixes take the affix ḍhak in forming their gotra (Patronymic).,
The word स्त्री in the aphorism means 'words ending in the feminine affixes टाप् &c.' That is, words ending in long आ and ई of the feminine. Thus विनता + ढक् = वैनतेयः 4.1.2. So also सौपर्णेयः \Son of Vinata or Suparni\. But ऐडविडः and दारदः formed by अण् meaning sons of इडविड and दरद, for though these words are feminine. they do not end in feminine affixes.
Vart:- The affix ढक् comes after वडवा when meaning वृष ॥ Thus वाडवेयः = वृषः \bull.\ Here 'dhak' has not the patronymic force. The patronymic will be वाडवः 'the son of a mare'.
Vart:- The feminine words क्रुञ्चा and कोकिला take the affix अण् in forming the patronymic. Thus क्रौञ्चः \the son of a curlew.\ कौकिलाः \the son of a cuckoo.\,