1) Sinistral 2) Sinistrorse 
• (a.) Rising spirally from right to left (of the spectator); sinistrorse.
Sin`is·tror'sal adjective [ Latin sinistrorsus , sinistroversus , turned toward the left side; sinister left + vertere , vortere , versum , vorsum , to turn.] Rising spirally from right to left (of the spectator); sinistrorse.