Natyashastra
अधोमुखीनां सर्वासामङ्गुलीनां समागमः । कनिष्ठाङ्गुष्ठकावूर्ध्वो स भवेत् मृगशीर्षकः ॥ ८६॥
Mṛgaśīrṣa (deer-head)—the Sarpaśiras hand with all its fingers pointing downwards, but the thumb and the little finger raised up.
english translation
adhomukhInAM sarvAsAmaGgulInAM samAgamaH । kaniSThAGguSThakAvUrdhvo sa bhavet mRgazIrSakaH ॥ 86॥
hk transliteration by Sanscript