108 Psyche [Sept. -Dec. 
hiatus, it is the uncus that I have selected (partly in develop- 
ment of Reverdin’s, Chapman’s, and Stempffer’s views) for 
differentiating species in the Lycoeides. 
The male armature consists of a dorsal (in regard to the 
body) portion (the uncus) and of a ventral one (the valves — 
which have a constant fishlike shape in the Plebejince). The 
two are hinged to each other somewhat in the way of the lids 
of a shell and appear “closed” when viewed in situ. When teased 
out of the tissues and viewed ventrally, i.e., when the whole 
organ is forced open oysterwise so that its symmetrically ex- 
tended valves continue to point down, whereas the uncus lobes 
point distad from the observer, the most conspicuous thing 
about the upper portion is the presence of a pair of formidable 
semi-translucent hooks (the subunci or falces — of a peculiar 
shape not found in allied genera), produced from the opposite 
side of the distally twinned uncus and facing each other in the 
manner of the stolidly raised fists of two pugilists (of the old 
school) with the uncus hoods lending a Ku-Klux Klan touch to 
the picture. The flame-shaped distal part of the candle-shaped 
aedeagus reaches a point between their elbows, while its proxi- 
mal part is propped by the fultura injerior (furca) at the root 
of the valves. 
In the paper already referred to, I introduced the following 
terms: F. for the length of the upright portion, or forearm , of 
the falx measured from its distal point to the apex of its elbow; 
H. for the length of the humerulus of the falx, from the apex of 
its elbow to the apex of its shoulder; and U. for the length of 
the uncus lobe from its distal point to the apex of the shoulder 
of the falx. In the majority of some 500 preparations, regard- 
less of whether the elbow of the falx happened to be raised (in 
the follow-through of an “uppercut,” to pursue the pugilistic 
image) as it is for instance in fig. ARG.A. of pi. 1, or whether 
it remained in its normal position {i.e. with the forearm parallel 
to the axis of the uncus lobe), a rather curious fact was noticed, 
namely that the distance between the tip of the falx and the 
apex of the shoulder exactly equalled U. This suggested the 
tracing of a triangle, FHU, its lines joining three points: apex 
of forearm, apex of elbow, and apex of shoulder. A glance at 
fig. 1 will show that, according to the dimensions of forearm, 
humerulus and uncus lobe, this triangle assumes a different 
size (showing the gradual generic development) and a different 
shape (showing the specific relative dimensions of parts). 
