Aoiatomy of the MnJe Genital Tube in Coleoptera. 593 



greater part of their length. Lateral lobes large, symmetrical ; 

 consolidated on dorsal and ventral faces at base. Basal-piece large, 

 tambour-shape with a ventral plate {vp) connected to the basal 

 ventral edges of the lateral lobes by membrane, not consolidated to 

 them. Internal sac large with four long thin diverticula at apex, 

 covered with hairs, no armature. 



We have examined several species of Hexodon and find they fall 

 into two groups, one with symmetrical lateral lobes and four 

 diverticula of sac ; the other with asymmetrical lateral lobes and 

 five diverticula. 



A ncognath a vi dgai -is. 



Median lobe moderate in size, membranous with chitinous 

 support near base. (In some Scarabaeidae the chitinous support 

 of the median lobe appears to appertain rather to the second 

 connecting membrane, but we have described it as belonging 

 to the median lobe as only a detailed study in many forms could 

 elucidate this.) Basal-piece of the usual tambour-shape, its con- 

 cave aspect membranous, its dorsal more feebly chitinised than in 

 the normal Dynastinae ; the sides of this sclerite prolonged distally 

 so as to form a point on each side to which are articulated the very 

 peculiar lateral lobes. These, viewed laterally form a sort of V, 

 between the branches of which the distal point of the basal piece (as 

 described above) penetrates. The lateral lobes are not in this species 

 amalgamated by chitin but exist as two sclerites connected by 

 membrane. Viewed on the convex aspect of the aedeagus in repose, 

 the two sclerites become contiguous, their inner margins being 

 nearly straight ; each is a little truncate at the tip, and on the outer 

 side has a small, sharp hook. On the concave aspect, the sclerite is 

 larger than on the other aspect, but the inner margins are parallel 

 here also. These lateral lobes are capable of divarication, and it 

 appears that this permits the extrusion of the median lobe. 



Internal sac large and complex, the apical half greatly enlarged, 

 with two small diverticula near opening of ejaculatory duct at apex, 

 and a long thin diverticulum opening near middle ; no chitinous 

 armature, but surface covered with short fine hair. 



Gyclocephala stictica. 



In this the lateral lobes are greatly abbreviated and form a ring 

 at the end of the basal-piece. This ring, being placed at a right 

 angle to the axis of the aedeagus, is articulated on each side to the 

 distal point of the basal-piece ; except at this spot the connection 

 of the lateral lobes with the basal-piece is entirely membranous. 

 As the ventral plate of the basal piece is to some extent elastic, 



