GENERAL CHARACTERS. 
5 
of a peduncle consisting of three joints, and a terminal 
multiarticulate filament, supplied with auditory cilia. Oc- 
casionally there is a second appendage, generally rudimen- 
tary, hut in some of the Phoxides it is of almost equal 
importance to the primary filament ; the secondary ap- 
pendage is, however, never furnished with auditory cilia. 
The posterior or inferior pair of antennae (c) consists 
of a peduncle of five joints and a multiarticulate fila- 
ment. The first two joints are closely incorporated, and 
bear an olfactory denticle ; but sometimes, as in Talitrus , 
the denticle is wanting, probably from the peculiarity of 
its condition of existence, as the Talitri do not live in 
water. Occasionally the terminal filament has the joints 
fused together. This numerical decrease is invariably 
attended with an increase of strength. 
In some genera of the Hyperina both pairs of antennae 
assume a rudimentary condition to such an extent that 
their respective parts cannot be readily defined : some- 
times even one or both may be absent. 
The jaws or mandibles ( d ) are placed between an 
anterior and posterior lip or labium ; they consist of a 
pair of curved triangular blades, each furnished with a 
cutting edge and a grinding tubercle. Within the inci- 
sive margin there is frequently a second movable plate, 
formed upon the type of the preceding. Each mandible 
has very generally, though not universally, an articulated 
palpus or appendage. The anterior pair of maxillae ( e ) 
consist of three or four foliaceous plates, whereas the 
second pair (/) have but two ; they are extremely deli- 
cate, and furnished, upon their anterior margins, with 
plumose hairs, some of which are strengthened into 
spines of various shapes. Exceptions to the normal 
forms exist in the Hyperina. 
The foot-jaws, or pedipalps (siagonopoda, I. O. W., or 
maxillipedes) {g) t are the posterior pair of appendages 
