What is "artiodactyla"

Artiodactyla \Ar`ti*o*dac"ty*la\, n. pl. [NL., fr. Gr. ? even + ? finger or toe.] (Zo["o]l.) One of the divisions of the ungulate animals. The functional toes of the hind foot are even in number, and the third digit of each foot (corresponding to the middle finger in man) is asymmetrical and paired with the fourth digit, as in the hog, the sheep, and the ox; -- opposed to Perissodactyla.