S1·E23 Tarzan and the Beast from Below

Terk gets scared when she sees a monster, which is later revealed to be a velociraptor from Pellucidar. The others initially dismiss Terk, but believe her after the dinosaur attacks the Professor's camp as well as Tarzan and Jane's treehouse. Tarzan attempts to find out how the velociraptor managed to get out of Pellucidar and how it can be sent back.