Original: Two species of crocodile occur in Kakadu: the Freshwater Crocodile (Crocodylus johnstonii) and the Estuarine, or Saltwater Crocodile (C. porosus).
Simplified: Two species of crocodile live in Kakadu: the Freshwater Crocodile (Crocodylus johnstonii) and the Estuarine, or Saltwater Crocodile (C. porosus).