śiraso 'vayavā nimnā vṛddhikāṭhinyavarjitāḥ // śaśaśṛṅgādirūpeṇa so 'tyantābhāva ucyate /
When the parts of [a hare's] head are flat and devoid of growth and hardness, that is called absolute non-existence, in the form of a hare's horn and such things;