A Comparative Study of the Appendages of the Eighth and Ninth Abdominal Segments of Insects

Abstract

This is a preliminary paper intended to establish the interordinal homologies of the genital appendages of insects more accurately and with greater certainty than has been possible in the past Much additional work on the subject is desirable in practically all of the orders of insects. While this paper was intended primarily as a study of the male gemtalia, it has been found necessary to consider first the structures of the ovipositor of female insects. Here the homologies appear to be relatively easily understood, and with the exception of one or two points, most authors agree in their interpretation of them Except where it seems advisable to use other names, the terminology employed by Snodgrass (1935) has been followed in this paper. FEMALES The ovipositor consists of the appendages of the eighth and ninth abdominal segments In the Apterygota such appendages apparently occur only m the Machilidae and Lepismidae. As shown in figure 3 each of these appendages in Machilis consists of a broad flattened coxopodite produced at the base of its inner margin as an endite or gonapophysis and bearing at its apex a musculated stylus. The stvli probably represent the telopodites of these appendages. (The similarly shaped but nonmusculated "styli" born on the coxae of the rear thoracic legs inv Machilis are apparently not homologous to the abdominal styli.) The broad basal plates may be known as coxites since each is only a part of the coxopodite, the other part being the gonapophysis. &