196 'Wisconsin Academy of Sciences, Arts, and Letters. 
put on record a few that have been seen in the course of the 
author’s systematic work on Copepoda. 
Plate X, figure 1 is a seta on the endopodite of the fourth 
foot of a specimen of Cyclops phaleratus Koch. It is evident 
that the seta was injured and the lateral which has grown out 
is the result of a regenerative process. Likewise plate X, fig¬ 
ure 2, may be explained as defective regeneration after an 
injury; this is the second segment of the exopodite of the fourth 
foot of Cyclops serrulatus Ficher. Normally there should be a 
single spine on the external margin instead of two. 
So, too, the abnormal terminal seta of Cyclops viridis var. 
americanus Marsh in plate X, figure 3, can be explained as the 
result of traumatism. 
In plate X, figure 4, however, we have a real monstrosity. 
This is the fifth foot of a specimen of Cyclops viridis Jur. col¬ 
lected in Pennsylvania. The second segment is normally armed 
with a short spine and a single long seta. Here we have a spine 
and two setae. This was not the result of injury and regenera¬ 
tion, for both fifth feet were of the same form. In all other re¬ 
spects the animal had the usual structure of Cyclops viridis . If 
there were any question of hybridization, it seems probable that 
other structures would have been affected. 
Plate X, figure 5, is the second segment of the exopodite of 
the right fifth foot of a male Diaptomus pallidus Herrick. Nor¬ 
mally the lateral spine is on the outside of the segment. In 
this case it is on the inside. There is nothing to indicate that 
this is the result of injury. 
Plate X, figure 6, is the second segment of the exopodite of 
the right fifth foot of a male Diaptomus sicilis Forbes. This 
has two terminal hooks instead of one. This specimen was 
from Green Lake, Wisconsin, and is the only one of the kind 
that has been seen, although great numbers of this species have 
been examined from many different localities. 
Another unique abnormality was seen in a specimen of 
Diaptomus minutus Lillj. found in Stone Lake, Wisconsin. 
This was a female with nothing unusual about its structure ex¬ 
cept its antennae which were those of a male, the right one being 
geniculated like the typical male antenna. 
