594 Mr, D. Sharp and Mr. F. Muir on the Comparative 
the annular lateral lobes can, by it stretching, be brought into 
the same plane as the axis of the aedeagus, 
The soldering together of the tips of the lateral lobes so as to form 
a perfect ring, make this very different from Ancognatha. The two 
forms have in common the unchitinised ventral plate of the basal- 
piece. 
It should be noticed that in this form the consolidation 
of the lateral lobes into a ring takes place in an indirect 
manner. The apices of the lobes meet very nearly, but 
not quite, and a distinct narrow space is perceived between 
them ; but basally to this small space the ventral plate 
penetrates between the lobes and is just there strongly 
chitinised, though elsewhere it is quite membranous. 
This is a very interesting case. If we make use of a 
teleological mode of expression we may say that it appears 
that the tips of the lateral lobes are in process of becoming 
consolidated so as to form a structure normal in Dynastinae 
(compare with X. gideon). The functional difference 
between Ancognatha and Cyclocephala appears to be that 
in the latter the orifice is held open permanently by the 
ring-shaped lateral lobes ; while in the more Melolonthoid 
structure of Ancognatha the lobes are mobile and the orifice 
opens or closes as the situation requires. 
Cyclocephala would from this point of view appear to be 
related to Xylotrupes, while Ancognatha points to an affinity 
with Diloboderus. 
Oryctes boas, 
The distal portion of the tambour is elongate and cylindrical, 
the basal portion broad and short. The lateral lobes are long, 
placed at a right angle with the cylinder, the orifice between 
them viewed from behind is elongate and rather narrow. The 
structure at the base of the median lobe is rather perfect; the 
chitinisation of its anterior:part on one aspect is met by a V-shaped 
prolongation from the other aspect, and by the conjunction of the 
two a complete ring-encasement is formed. We have already stated 
that we have not been able to decide as to the nature of this 
chitinisation. 
Diloboderus abderus. 
The aedeagus is here short, broad at the base, and gently 
narrowed to the tip so as to be somewhat conical in form viewed 
dorsally. The lateral lobes are articulated so as to admit of a 
