रथीतराणां प्रवरा: क्षेत्रोपेता द्विजातय: ॥ ३ ॥
punas tv āṅgirasāḥ smṛtāḥ
ete — the sons begotten by Aṅgirā; kṣetra-prasūtāḥ — became the children of Rathītara and belonged to his family (because they were born from the womb of his wife); vai — indeed; punaḥ — again; tu — but; āṅgirasāḥ — of the dynasty of Aṅgirā; smṛtāḥ — they were called; rathītarāṇām — of all the sons of Rathītara; pravarāḥ — the chief; kṣetra-upetāḥ — because of being born of the kṣetra (field); dvi-jātayaḥ — called brāhmaṇa (being a mixture of brāhmaṇa and kṣatriya).
Having been born from the womb of Rathītara’s wife, all these sons were known as the dynasty of Rathītara, but because they were born from the semen of Aṅgirā, they were also known as the dynasty of Aṅgirā. Among all the progeny of Rathītara, these sons were the most prominent because, owing to their birth, they were considered brāhmaṇas.
Śrīla Viśvanātha Cakravartī Ṭhākura gives the meaning of dvi-jātayaḥ as “mixed caste,” indicating a mixture of brāhmaṇa and kṣatriya.