220 THE ENTOMOLOGIST. 
Reverdin, with his greater command of material, to demonstrate 
their constancy. The genitalia of the Norfolk alveus present 
exactly the same differences from those of the mountain alveus 
that one finds in armoricanus, and it should therefore be known 
by the latter name. | 
The most reliable distinction between alveus and armoricanus 
lies in the form of the edeagus-guides. These are paired organs, 
apparently hung from the roof of the tegumen, but really pro- 
ceeding from the diaphragm which closes the end of the body, 
one on each side a little above the edeagus. In the lateral 
aspect they appear as irregularly oblong lobes with small crowded 
irregular teeth on their upper edge. They proceed from a wide 
base which on the inner side is in contact with its fellow, and, 
with the exception of a space on the basal half of the upper side, 
b 
J. E. del. 
are highly chitinised. In alveus the guides are twisted so that 
the lower edge, instead of lying directly beneath the upper edge, 
lies considerably to the outside of it, and is distinctly reflexed, 
so that the surface appears to be broadly concave. In armoricanus 
the guides are approximately flat, their upper and lower edges 
lying in practically the same plane. These conditions may be 
observed either in the cephalo-vertical or the lateral aspect; but 
they are not to be seen in any photographs of slide-preparations 
that I have seen. The use of the term edeagus-guides for the 
parts in question was suggested by their appearance when in 
situ; they are the ‘‘apophyses laterales de lUuncus” of Prof. 
Reverdin, and have also been referred to as the scaphium ; though 
why the latter term should be applied to paired organs is not 
clear. 
I have to thank Mr. Rowland-Brown for placing at my disposalh 
authentic examples of H. armoricanus. 
