अग्निनिचयः (Agninichaya) / The Accumulation of Sacred Fire & the Classification of Pitṛs by Time-Order
मासाः षडर्तवो ज्ञेयास्तेषां पञ्चर्तवाः स्मृताः / द्विपदां चतुष्पदां चैव पक्षिणां सर्वतामपि
māsāḥ ṣaḍartavo jñeyāsteṣāṃ pañcartavāḥ smṛtāḥ / dvipadāṃ catuṣpadāṃ caiva pakṣiṇāṃ sarvatāmapi
From the months one should know the six seasons; and among them five are remembered as ārtava—pertaining to bipeds, quadrupeds, and birds, in all their kinds.