Gāndharva-lakṣaṇa
Traits/Classification of the Gandharvas) and Royal-Genealogical Continuities (Vamśa-prasaṅga
शशादस्य तु दायादः ककुत्स्थो नाम वीर्यवान् / इन्द्रस्य वृषभूतस्य ककुत्स्थो जयते पुरा
śaśādasya tu dāyādaḥ kakutstho nāma vīryavān / indrasya vṛṣabhūtasya kakutstho jayate purā
Śaśāda’s heir was the mighty one named Kakutstha; in ancient times Kakutstha was born of Indra, who had assumed the form of a bull.