_ Anatomy of the Male Genital Tube in Coleoptera. 595 
beautiful movement of a limited nature. In repose they are 
brought near together, and their inner dorsal margins lie paralle} 
though separated by a good space. If a little pressure be applied 
inside the aedeagus at the point where they meet dorsally, the two 
lobes separate by a partial rotation and then disclose a broad orifice 
such as we find to be the fixed position in Xylotrwpes gideon. The 
specimen is in very bad condition, but we mention it because we 
have not observed a similar peculiarity in allied forms, though it 
may not improbably be found to exist elsewhere in the higher 
Dynastinae. The form and general proportions of the aedeagus are 
similar to those of Oryctes boas. Some special experiments made 
with that species show that the lateral lobes can be forced apart to 
a considerable extent by pressure, but there is no rotation whatever, 
and the parting is due to the elasticity of the ventral plate connecting 
the lobes, 
AXylotrupes gideon (Pl. XLVI figs. 26, 26a and 26D). 
Median lobe large, membranous, with chitinous ring at base for 
support, prolonged into a pair of median struts, consolidated at their 
base. Lateral lobes consolidated on dorsal and ventral side, short 
forming a short ring or tube which projects on the ventral side as 
two short, flattened and truncate points, which have a slightly out- 
ward turn, Though the lobes are thus separated at their distal part, 
they are united, in front of the free processes, to form a ring. Basal- 
piece large, tambour-shape, constricted about the middle, with a 
ventral plate (vp) which is only consolidated to the lateral lobes at 
the corners (a).* Internal sac large with two large, strong, curved 
spines about the middle. 
We have examined several specimens of this well-known insect ; 
they come from different localities, and there is slight variation in 
the aedeagus, 
Three males from Koberi (N. Guinea, Pratt), one of them the 
fullest development of the species, the other two moderate, agree 
closely except that the largely developed example has the distal 
portion of the tambour more elongate, and the tusks of the lateral 
lobes less abruptly turned backwards, 
A single specimen from “ Australia” (old coll.), is of the broad, 
robust variety of the species, with broad thoracic horn, and the forks 
of the cephalic horn strongly developed ; it has the aedeagus much 
as in the moderate Koberi form, but a little shorter and thicker, the 
* In fig. 26 the point (a) appears to overlap the lateral lobe: this 
is not correct ; ‘‘a” only reaches the margin of the lateral lobe, and 
is there conjoined with it, 
