622 Fresh-Water Entomostraca. [ October, 
served, often a delicate, transparent animal may be seen darting 
about in the vessel like a flash of light, or if the lake be shal- 
low and abounds in water plants the related form represented 
in Plate 1 may be seen. As it springs from side to side of the 
jar it seems a living jewel, for the antennze and abdomen are 
tipped with varying purple, and the body glows yellow and 
scarlet, and if the bright-red egg-mass be present it is a con- 
spicuous object. Place it under the microscope with a low power 
and we can see the long flexible antennz, and if it is a male the 
thickened basal joints can be seen terminating in a spine at the 
thirteenth, where the geniculating joint is situated. The anten- 
nules on either side of the head segment, which is distinct from the 
thorax in this species, and the stylets on the last joint of the 
abdomen, with their seta, are noted—when the antennules begin 
to rotate like the paddles of a steamer, and bending the abdomen 
and immediately launching a powerful “kick” with the caudal 
sete spread out, at the same time that the antenna beat the 
water like oars in the hands of an expert, the animal springs out 
of sight. One instinctively looks for the fellow some yards 
away, but remembering that the whole animal is little over .06 
of an inch long, we again adjust the slide and bring him into view. 
More abundant than the Diaptomus and better known, is the 
Cyclops. Plate 11 represents a large species in which the hairs 
are greatly elongated, especially on the caudal sete, the longest 
pair of which resemble feather dusters. The Cyclops has received 
more than its share of names, owing to the great difference 
between different stages of its existence. If we place a female 
Cyclops in a vial, in a few- days little specks will be seen swim- 
ming about in the water, and the eggs will have disappeared. 
These specks prove to be the young of Cyclops, but so little like 
the parent that it requires much faith to believe they will ever 
assume its likeness. Instead of five pairs of feet there are but 
three, and as we watch the growth of the animal, these prove to 
be elementary antennæ and jaws, while the true feet bud out of 
segments not yet formed. Almost every pool furnishes another 
example of the Cyclopoidea in the Canthocamptus which resembles 
the Cyclops greatly, and goes through the same transformations. 
The body tapers gradually with no marked distinction between 
thorax and abdomen ; the egg-sac too is under the abdomen, and 
has in connection with it a colorless tube. 
Perhaps the next animal to attract our attention will be a crea- 
