4 
78 THE NORTHERN MICROSCOPIST. 

or any other bivalve mollusk. But bear in mind this is nota 
mollusk ; it is a crustacean enclosed in bivalve shell, as we shall 
hereafter prove. 
By applying your Coddington or platyscopic lens to those valves 
you will see that they are invariably prettily marked with small 
pittings either all over, or at the end only, and you will sometimes 
find that the valves are fringed on the margins with a delicate row 
of fine hairs which undoubtedly act to filter the water as it passes 
inwards to the animal. Now remove your Cypris to the microscope, 
and whilst there take away the valves, and lay bare the structure of 
the little animal, and, astonishing fact to the uninitiated, we find 
him built up on the same structural platform as the lobster. Do 
not misunderstand; we do not mean to say that he is either a 
young lobster, or a degenerated form of it, but that the general 
arrangement of his organs is the same. In the lobster we have 
the abdominal parts segmented, which segments are visible by 
reason of the close adherence of the shell to the body, and being 
jointed move about with the action of the several segments. In 
the lobster we have also segments of the body fused together, 
forming one hard covering to the vital parts of the creature, and, 
further, we have in the lobster certain appendages which we all 
recognise as antenne, claws, and feet. 
Now, in the Cypris we do not find any close-fitting, hea seg- 
ments, movable with the various parts of its body, but in the 
place of these we have the hard, brittle little shell covering the 
delicate body within, from which shell when opened project its 
antenne and feet, which serve the same office to the Cypris as do 
those organs to the lobster. 
According to Brady, the anatomical structure of the Ostracoda, 
and consequently of the Cypris, is as follows :—It has a pair of 
upper antennze which are seven-jointed, and have at the end a set 
of beautifully fine hairs, long and graceful, which have the power 
of beating the water and creating a current, probably for the pur- 
pose of bringing small prey within reach of the animal. It has a 
second pair or lower antennz which are stouter than the first, and 
is geniculated or bent back. These antenne are clawed, which 
makes it adapted for walking, and have also a lash of hairs which 
adapts the creature for swimming. No doubt the hairs upon the 
first antennze will also assist in this office when required, and con- 
jointly will mainly cause the rapid motion which we observed at 
the outset. There is also a pair of feet which project beyond the 
shell when in use, and, being clawed at the extremity, assist the 
lower antennee when in the act of walking. 
All the foregoing organs are used externally, as are the similar 
organs in the lobster. 
Within the valves are the mandibles, which are elongated and 
