2135 
thorax. In the Iulgoroidea the hind coxae are immobile and 
their exterior part is coalesced with the metathorax. 
In all the Cicadoidea, with the exception of the Cicadellidae, 
and in all the Sternorhynchi, one finds a wonderful arrangement 
of the alimentary tract whereby the posterior portion of the mid- 
gut is brought into intimate contact with part of the crop. This 
allows certain of the more fluid contents of the crop to pass 
through the walls of the crop and mid-gut by osmosis, the more 
solid portion passing through the intestine and undergoing diges- 
tion. The fact that the Membracidae possess a filter or colum 
and the Cicadellidae do not, although they are otherwise so 
closely related, is difficult to account for. The simplest way 
would be to consider that they have lost it since parting from 
the main stem. But we have no evidence at present that they 
have, so we must give this distinction weight when considering 
phylogeny. The Fulgoroidea and the Heteroptera possess no 
sign of a filter. 
In the Cicadoidea and in the Delphacidae and in part of the 
Cixiidae the ovipositor is complete, the anterior and middle pair 
of processes (the latter amalgamated into one in whole or in 
part) are fastened together by a tongue and groove so that they 
work as a single organ. In the remainder of the Fulgoroidea 
and the Sternorhynchi the ovipositor is greatly reduced or in- 
complete, the anterior and middle pair are not co-ordinated, and 
often the three pairs are rudimentary or are entirely absent. 
The complete ovipositor is the primitive type among the Homop- 
tera. The incomplete ovipositor often has secondary adaptations 
for cutting into plants for depositing their eggs. 
The male genitalia are much more complex and difficult to 
understand. Our present knowledge stands as follows: 
The genitalia of the sexes are homologous in so far that they 
arise from similar processes situated in the same position on the 
abdomen. Their relationship is as tabulated below, where g 1 
is the anterior, g 2 the median, and ¢ 3 the posterior processes 
or gonapophyses. 
Female Male 
g 1. Guides of ovipositor Genital plates, often amalgamated 
to pygofer 
g 2. True ovipositor Aedeagus 
g 3. Ovipositor sheaths Genital styles 
