Skandapurana 16.23.40

16.23.40

sthāvaraḥ sarpajātiśca pakṣijātistathaiva ca ..
mṛgasaṃjñaścaturthaśca paśvākhyaḥ pañcamaḥ smṛtaḥ .. 7.1.23.40 ..

inanimate beings, serpents, and likewise birds; / beasts of the wild are counted as the fourth, and domestic animals as the fifth;