In Greek mythology, Orthrus (Greek: Ὄρθρος , "Orthros") or Orthus (Greek: Ὄρθος , "Orthos") was, according to the mythographer Apollodorus, a two-headed dog who guarded Geryon's cattle and was killed by Heracles. He was the offspring of the monsters Echidna and Typhon, and the brother of Cerberus, who was also a multi-headed guard dog.
Orthrus was a species that belongs to the feline class. 
( z1 species :name ( z2 name :op "Orthrus" ) :ARG1-of ( z3 include :ARG2 ( z4 class :mod ( z5 feline ) ) ) )