260 HISTORY OF BRITISH CRUSTACEA. 
The Apus swims on its back as easily as on its lower sur- 
face, using the feet, which are constantly in motion. Its 
food seems to be chieflv the smaller kinds of Entomostraca , 
the shells of which they can readily break with their man- 
dibles. Their eggs retain their vitality for a great while ; 
as the little creatures have been known to appear in a ditch 
that was suddenly filled with water after having been dried 
up for two or three years. 
Gen. 136. APUS, Scopoli, 
Plate XY. fig. 1 a , shows the head viewed in front. 
Apus cancriformis, Schaeffer. ShielcUShrimp, (Plate 
XY. fig. 1.) — Brownish-yellow, clouded with darker colour; 
shield covering more than half the body, ovate. 
Hab. Pond on Bexley Common. Devonshire, Bristol. 
(Baird, 1. c. p. 31.) 
Pam. NEB A LIADJE, Leach . 
Antennae two pairs, large and branched ; eyes two, pe- 
dunculated ; twelve pairs of feet, eight for breathing, and 
four for swimming. Carapace large, enclosing the head, 
thorax, and part of the abdomen, as if in a bivalve shell. 
