THE CANADIAN F.NTOMOLOCIST 170 



America, XII, 1919, p. 2()7) is incorrect in adopting the method of designating 

 the basal segment of the cerci as tlie "hasipodilc," i)roposed by the Cierman 

 entomologists. Furthermore, it is quite possible lluil the paraprocts them- 

 selves (or a portion ol them) represent the basal region of the uropod (see Fig. 

 5, "e"), whose endopoditc is represented 1)>' the cerci. If this be correct, we 

 might also consider the styli-like "paraprocessi',, or articulated processes borne 

 on the paraprocts of i-crtain tridaclylids, as the representati\'es of the exopcxlite 

 ol the uropod whose cndopodite torms the cerci of these insects. 



The st>li of insects apparently represent the exopodites of abdominal 

 limbs, and if the paraprocessi also represent the exopodites of abdominal limbs 

 (uropods) we would naturally expect that those paraprocessi would have the 

 lorm of st\ii — as is true of the jointed paraprocessi of the tridactylids. On 

 the other hand, the paraprocessi of certain Plecoptera are not styli-like, and the 

 so-called suprahami (or surhami) of certain Blattida, which are somewhat 

 suggesti\'e of them, are not styli-like, being more like a hook — but the type of 

 structure occurring in the Plecoptera might possibly be regarded as modifications 

 ol the original styli-like form. It ma\' l)e remarked, in passing, that in some 

 larvie these styli have been interpreted as "cerci"; but this matter will be 

 discussed eslewhwere. 



The tenth tergite, "lO"', of Figs. 1 and '), has been referred to as the "epi- 

 jM-()Ct," or supraanal plate, when it is sufficiently well developed to be dis- 

 tinguishable, although the same term has also been applied to the eleventh 

 tergite "ll*^" in some cases. This is a somewhat lax application of the term 

 epiproct, and Walker, 1919 (I. c.) is much more exact in restricting the designa- 

 tion epiproct or supraanal plate to the eleventh tergite. There is, however, 

 an apparent need for some general designation for the last visible tergite no 

 matter to what segment it belongs, and on this account I have here followed the 

 more lax usage of referring to the apparent terminal tergite as the "epiproct" 

 regardless of the segments involved in its make-up. In the sawflies, the tenth 

 tergite "10"' of Fig. 3 is usually more or less closely united with the ninth 

 tergite, and in most higher insects it is difificult to identity its homologue. The 

 sternum of the tenth segment is usually greatly reduced or atrophied, although 

 it is claimed by some entomologists tiiat the basal ijortion of the genital forceps 

 "a" of Fig. 2, represents the tenth sternite in sawflies, etc. I think, how^ever, 

 that it is possible to interpret the structure in cjuestion in another way, as will 

 be presently discussed. Heymons and others have maintained that lateral 

 structures of the tenth segment form what appear to be the cerci in male Odonata, 

 and there are sometimes present in certain phasmids, accessory lateral clasping 

 organs which might be mistaken for cerci, though in reality they are merely 

 posterior prolongations of the lateral region of the tergite. 



Lateral portions of the ninth tergite may become prolonged posteriorly 

 to form the surgonopods ("i" of Pig. G) or accessory clasping organs of certain 

 Neuroptera, Diptera and related forms, and ha\e, in some cases, been mistaken 

 for the true genital forceps when the latter are reduced and the surgonopods 

 are well developed. The pleural region of the ninth segment laljeled "9^" in 

 Fig. 6, has been homologized with the paraprocts "e" (Figs. 1, 3, 5, etc.) in 

 certain higher insects; but the gonopleurite "9^"' of Fig. ti, is an entirely dif- 

 ferent structure, and should be designated by a term indicating this fact. The 



