544 Mr. D. Sharp and Mr. F. Muir on the Comparative 



two lobes having dorso-lateral positions and the third a ventre- 

 median one, this lobe is continued as a narrow, thin plate having 

 a narrow edge of chitiu ; 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 cervinug) the median lobe is repre- 

 sented by a pair of processes rising from the edge of the median 

 orifice. The tegminal fold is 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. 



Cyplion coarctatus (PL LXXI fig. 188). 



When the aedeagus is fully drawn out the 8th and 9th abdominal 

 segments are distinct, the tergites plain, and well chitinised Avith 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 tliis structure are difficult to make 

 out, as owing to the absence of a distinct tegminal fold 

 there is no guide. Hclodes 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 Microcara {Helodcs) and the tegraen 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, 

 etc., 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 



