Protopodite, endopodite, exopodite, and epipodite were considered to be the morphological units of the crustacean limb.
The endopodite (corresponding to the fifth endite of the limb of Apus, see fig.
(4) Three of the rami of the primitive limb (endites 5 and 6, and exite I) specially developed as endopodite, exopodite, and epipodite - the first two often as firm and strongly chitinized, segmented, leg-like structures; the original axis or corm reduced to a basal piece, with or without a distinct gnathobase (endite i)- typical tri-ramose limb of higher Crustacea.
(5) One ramus (the endopodite) alone developed - the original axis or corm serving as its basal joint with or without gnathobase.
(6) Two rami developed (usually, but perhaps not always, the equivalents of the endopodite and exopodite) supported on the somewhat elongated corm (basal segment).