4 Annals of the South African Museum. 



Hymenoptera is not a true thoracic segment, but is composed of an 

 abdominal segment which has shifted forwards during embryonic 

 development. Hence arises what at first sight appears to be a 

 needlessly confusing terminology of the different parts. Since the 

 posterior portion of the thorax, variously termed the propodeum, 

 epinotum, middle segment, metanotum, etc., is in reality the true 1st 

 abdominal segment, the 1st joint of the petiole is therefore the true 

 2nd abdominal segment. For taxonomic purposes, and more partic'u- 



Fm. 2. 



Thorax of Pachycondyla Krugeri, 

 Forel. s • 



pn = pronotum. 



sc = scutum of mesonotum. 



M.f = Mayrian furrows. 



ps = parapsidal furrow. 



p = parapsis. 



set = scutellum of mesonotum. 



met = metanotum. 



ep = epinotum. 



tfj = tegula. 



Fig. 3. 



Streblognathus aethiopicus. 5 . 

 Seen obliquely from the side and above. 



d = dorsum "i 



s = side J- of epinotum. 



/ = face or declivity) 



n = node of petiole. 



vl = ventral lamella of petiole. 



1 = 1st abdominal segment. 



mes = mesonotum. 



pr = pronotum. 



larly in dealing with the comparative dimensions of head, thorax, 

 and abdomen, the epinotum is regarded as a part of the thorax, the 

 petiole (whether of one or two joints), is treated of as a distinct 

 region, and the 1st segment behind the petiole is described as the 

 1st abdominal segment. The latter is termed by some authors the 

 post-petiole, and the segment following it is in that case called 

 either the 1st abdominal segment or simply the 2nd segment. In 

 this work, the segment following the petiole, whether the latter be 

 of one or two joints, will always be treated as the 1st abdominal. 

 A glance at Fig. 1, p. 3, will explain more clearly the terminology 

 adopted. 



