CYPRIDINA. 
179 
alive, and resembled, he says, “ those small insects called 
in France puces d'eau ” The body of the animal was 
contained in a little shell, which was transparent, and 
resembled in form an almond cleft on one side, and 
notched at the superior part. The animal, besides several 
organs, which he shortly describes, had, he remarks, “ a 
large foot, armed with a toothed talon, resembling that of 
th z puce d’ eau, and destined for the same uses, being a 
kind of rudder, which enables the insect to move about 
with swiftness/’ Such appears as yet to be the whole 
amount of our knowledge with regard to the habits of this 
genus. 
1 . Cypridina Mac Andrei. Tab. XXII, fig. 1 a-g. 
Cypridina Mac Andrei, Baird , Ann. and Mag. Nat. Hist., 2d series, 
i, 21, t. 6 b, f.1-7, 1847. 
The shell or covering is of an oval shape, the two ex- 
tremities prolonged into sharp points ; that of upper 
extremity curved and projecting forwards, and a little 
upwards, that of inferior extremity projecting a little back- 
wards. The whole surface of the valves is dotted over with 
small points, and on their anterior edge, near the upper 
extremity, they are deeply notched. The eyes are ovoid- 
shaped, and areolar. 
The first pair of antennae (t. XXII, f. le ) is of con- 
siderable length, and consists of five articulations. The 
basilar joint is the longest and largest ; the second is of 
nearly equal size, and armed on its external edge with 
five or six short setae ; the third is the shortest ; the fourth 
is about twice the length of the preceding, and like it 
sends off two or three short setae at the extremities ; and 
the fifth, or terminal, has at its extremity six or seven long 
setae, which are not plumose. The second pair of antennae 
(t. XXII, f. 1 c ; t. XXIII, f. I c) is about two thirds 
the size of the first pair, and is divided into four articu- 
lations. The first, or basilar joint, is stout, and of consi- 
