544 Mr. D. Sharp and Mr. F. Muir on the Comparative 
two lobes having dorso-lateral positions and the third a ventro- 
median one, this lobe is continued as a narrow, thin plate having 
a narrow edge of chitin; the end of the ejaculatory duct (or un- 
differentiated internal sac) lies on this plate and has a wide opening 
on a membrane between the two dorso-lateral lobes. 
This median portion we consider is the median lobe. In certain 
of the Dascillidae (i. e. Dascillus cervinus) the median lobe is repre- 
sented by a pair of processes rising from the edge of the median 
orifice, The tegminal foldis quite distinct, separating the median or 
distal portion from the basal and outer portion, and it is highly 
probable that it is homologous to the same fold in other types. 
Cyphon coarctatus (Pl. LX XI fig. 188). 
When the aedeagus is fully drawn out the 8th and 9th abdominal 
segments are distinct, the tergites plain, and well chitinised with a 
strut from each posterior corner. The sternites not so well defined. 
The anus lies beneath the ninth tergite, and the structure between the 
anus and the ninth sternite is the aedeagus. This structure consists 
of a membranous tube with a very large orifice (median orifice), the 
opening of the ejaculatory duct or undifferentiated internal sac. 
On the dorsal side this tube is supported by a chitinous V or Y 
piece, on the ventral edge there are two curved chitinous hooks 
which are extended inwardly as a broad thin plate. 
The homologies of this structure are difficult to make 
out, as owing to the absence of a distinct tegminal fold 
there is no guide. Helodes is the nearest type to which 
we can refer it. Considering the opening of the ejacu- 
latory duct as homologous in these two forms then the 
curved hooks and plate would be equivalent to the lobes 
and plate of Mierocara (Helodes) and the tegmen would 
not be represented at all. Until more Dascillid and 
allied forms have been studied this is the best explanation 
we can give, but we fully recognise its weakness. 
By the structure of the undifferentiated internal sac, 
ete., we had considered it probable that copula did not take 
place in the usual manner in this form, but that it was 
possible that the female “ ovipositor” was inserted into 
the large median orifice. An observation of the senior 
author adds strength to this supposition, but it needs 
more confirmation; any observations of the copulation of 
Dascillids, Cyphonids and their allies will be of interest, 
especially as to the part played by the “internal sac.” 
We hope that one of us may be able to elucidate this 
