Anatomy of the Male Genital Tube in Coleoptera, 571 
reaching beyond the ends of the median struts, with a stout, curved, 
spine-like flagellum at the apex and a large diverticulum (a) below 
it. 
Polycleis plumbeus. 
Median lobe well chitinised, tubular, slightly flattened and 
curved ; ventral edge of median orifice projecting beyond dorsal 
edge and bluntly pointed; median struts small and slender, only 
half as long as the median lobe. Tegmen forming a ring-piece 
with a pair of small delicate projecting lobes on dorsal aspect and 
a slender central strut on ventral aapedl: Internal sac contained 
within median lobe. 
With the increased chitinisation of the median lobe there is 
here a reduction of the median struts. 
Lrachycerus apterus. 
Median lobe forming a short flattened tube, with the ventral edge 
of median orifice projecting beyond the dorsal edge and pointed ; 
median struts large. Tegmen forming a ring-piece with lateral 
lobes consolidated into a cap-piece on dorsal aspect ; central strut 
on ventral aspect large. Internal sac long with armature which we 
have not examined. 
Belus bidentatus (Pl. LX XVI fig. 223). 
Median lobe forming a straight chitinous tube, with a pair of short 
median struts; median orifice at apex. Tegmen forming a wide 
ring-piece with a long narrow cap-piece ; central strut large. Internal 
sac long, projecting some way beyond the median struts. A fine 
chitinous tube (a) projects through the apex of the sac, and ends in 
a membranous flagellum (fy) ; the chitinous tube (a) appears to have 
the power of being moved through the apex of thesac. The apex of 
the sac is supported by two crescent-shaped sclerites ()), one on each 
side of the tube. The dorsal and ventral aspects of the internal 
sac are supported by two chitinous plates from near the apex to the 
base. 
The long, slender sac with the flagellum at the apex 
recalls the highly specialised flagella and long sacs of the 
Brenthids. 
Sphenophorus obscurus (Pl. LX XVI figs. 224, 224a). 
Median lobe forming a semi-chitinous tube, supported along each 
side by a chitin strip (a), the median orifice is at the apex on the 
dorsal face and is supported by a chitinous ring. From the basal ends 
