18 
BRITISH ENTOMOSTRACA. 
varying from eleven pairs to sixty in number ; articula- 
tions foliaceous and branchiform, being chiefly adapted 
for respiration and not for locomotion ; eyes, generally 
two, but sometimes three, in some situated at the extre- 
mity of moveable pedicles ; antennae, sometimes only one 
pair, but usually two, generally small, and not fitted for 
assisting the animal in swimming ; mandibles for the 
most part without palpi. 
Family 1 — APODIDiE. 
Apus, M. Edwards, Hist. Nat. Crust., iii, 356, et auctorum. 
Phyllopoda, Leach , Edin. Encyelop., vii, art. Crustaceology. 
ApoDiDiE, Burmeister, Organization of Trilobites, 34. 
Character . — Antennae one pair, short and styliform ; 
eyes three, sessile ; feet, sixty pairs, all branchial ; nearly 
the whole body covered by a large shield-formed carapace • 
body composed of numerous rings or joints. 
Bibliographical History . — The first notice we find taken 
of any species of the genus Apus, is by Jacob Frisch, in 
his ‘ Insecten in Deutschland/ tom. x, published at Berlin, 
in 1732. He there gives a figure and description of an 
insect, which he calls “ vom Floss-fussigen seewurm mit 
dem Schild/’ A specimen, he informs us, was sent to 
him, well preserved in spirits, from Dantzic, by Klein, 
who was then secretary of state. In this notice he indi- 
cates, though rather vaguely, the use of the word Apus, 
— a name which has since been given to the genus, and 
by which it is now known. Soon after this, Klein sent a 
short notice, with a tolerable figure of the same insect, in 
a letter to Sir Hans Sloane, which was published in the 
'Philosophical Transactions’ for 1738. In this letter he 
says that it was found at Uderwanga, in East Prussia, 
amongst fresh- water crayfish, and that, from the great 
number of its legs and their extreme mobility, he was 
induced to call it the Scolopendra aquatica scutata. <£ As 
long as the insect lives,” he says, “ so long does it continue 
