Anatomy of the Male Genital Tube in Coleoptera, 515 
Tegmen (fig. 85a) forming a ring-piece, the dorsal part being a hood- 
shaped body, with a thin piece proceeding from each basal corner and 
consolidating on ventral side of median lobe. Internal sac very 
large, bearing armature near base (b) and towards apex (a). 
Family NITIDULIDAE. 
Forms examined: Psilotus atratus Reitt., Chiriqui. 
Cychramus luteus Fabr., England. Jps (Glischrochilus of 
various authors) japonius Motsch., Japan. 
Figs. 87 and 88 Pl. LVI. 
Psilotus atratus (Pl. LVI fig. 87). 
Median lobe tubular, broad and flat, with single median strut. 
Tegmen forming a large broad curved plate or hood, on dorsal 
face, with a small dorsal median projection (a) from base, the basal 
corners meeting and consolidating on ventral side of median lobe. 
Internal sac large, the opening of ejaculatory duct at apex, where it 
is supported by two chitin rods consolidated together at tip (b) round 
the duct opening. 
Ips japonius (Pl. LVI fig. 88) 
is of the same type as P. atratus; and so is Cychramus, the “ hood’ 
being much larger than the median lobe, ) 
The family Monotomidae comes near to these forms, 
as also does Helotidae. On the other hand, Rhizophagus 
does not belong to Nitidulidae. Whether it can be 
satisfactorily placed in Cucuwjidae (where we have treated 
of it, cf. fig. 101), can only be determined by a much 
more extensive survey of the Cucujidae than we have 
made. 
Family BYTURIDAE. 
Form examined: Bytwrus tomentosus Fabr., England. 
Fig. 86 Pl. LVI. 
Byturus tomentosus (Pl, LVI fig. 86). 
Median lobe long, ‘slender, and pointed; median orifice at tip on 
dorsal face; median foramen at base. Tegmen forming a close- 
fitting sheath, the distal half chitinous, the basal half membranous, 
with a strip of chitin supporting each side (a); and a Y-piece 
with a long stalk (b) supporting the ventral aspect. Internal sac 
undifferentiated, 
This type is similar to Trogositidae. 
