112 
BRITISH ENTOMOSTRACA. 
Polyphemus stagnorum, Leach, , Diet. Sc. Nat., xiv, 540. 
— Latreille, Cuv. Reg. An., iv, 165. 
— Desmarest, Cons. gen. Crust., 365, t. 54, 
f. 1. 
Polyphemus pediculus, Straus , M6m. Mus. d’Hist. Nat., v. 
— M. Edwards, Hist. Nat. Crust., iii, 389. 
Monoculus polyphemus, J urine. Hist. Nat. Monoc., 143, 1. 15, f. 1-3. 
Cephaloculus stagnorum, Lamarck, Hist. An. s. Yert., v, 131. 
— Bose, Man. d’Hist. Nat. Crust., ii, 247. 
Le Monocle 1 queue retroussee, Geoffroy , Ins. Par., ii, 656, No. 2. 
Monoculus oculus, Gmelin, Linn. Syst. Nat., edit. 13th, i, 2996, 
No. 10. 
Scalicerus pediculus, Koch, Deutsch. Crust., h. xxxvii, t. 2. 
The body is oval-shaped, separated from the head by a 
deep indentation. 
The upper part of the head is almost entirely occupied 
with the eye, which is provided with its rotatory muscles, 
as in the Daphniadae, and is beset, all round the upper and 
outer edges, with numerous lucid areolae, about twenty in 
number. The lower part is quite transparent, the black 
mass filling only about three fourths of the whole. 
The mandibles are almost exactly the same as in the 
Daphnia. 
The inferior antennae or rami (t. XVII, f. 1 a) are large, 
and divided each into two branches. The anterior branch 
has three articulations : the first the largest ; the second 
is the shortest ; and the third is the longest and the most 
slender. The first joint has one seta, the second one also, 
and the third has two from the side, at equal distances from 
each other, and three from the apex. The posterior branch 
has four articulations, one very short and three longer. The 
second joint has one seta at its extremity ; the third has 
one springing from the middle of the articulation, and one 
from the extremity. The last joint has one seta on its 
edge, and three at its extremity. The setae are jointed at 
about half the length. 
The superior antennae are small, arising from the edge 
of the head below the eye ; they are sharp-pointed, and 
terminate in two or three fine setae, directed upwards. 
