Three types of growth pattern in the odonate antenna are described. These differ from each other in the order in which the unique division (A) of the apical segment, and the 3 successive divisions (B) of the basal segment of the flagellum take place during larval development. These types correspond to higher taxa of the Order, viz (1) the B.B.B.A type is found in the Coenagrionidae, Petaluridae and Aeshnidae; (2) the B.A.B.B type in Cordulidae and primitive Libellulidae; (3) the B.B.A.B. type in higher forms of Libellulidae, with a transitional type between (2) and (3) in some sympetrine species. In this respect the Order can be divided into 2 groups: Zygoptera-Petaluridae- Aeshnidae on one hand, Corduliidae-Libellulidae on the other.