The Compendium of Caraka 6.23.130

6.23.130

vṛttabhogo mahākāyaḥ śvasannūrdhvekṣaṇaḥ pumān/
sthūlamūrdhā samāṅgaśca strī tvataḥ syādviparyayāt//

Having round coils, a large body, hissing, and looking upward, is the male; / with a thick head and symmetrical limbs, while the female is the reverse of this.