84 
ZOOLOGY. 
numy simple eyes, each consisting of a cornea and crystal- 
line cone, connected behind with a long, slender connective 
rod, uniting the cone with a spindle-shaped body resting 
on or against an expansion of a fibre of the optic nerve, 
and is ensheathed by a retina or black pigment mass. 
The lobster's ears are seated in the base of the smaller 
or first antennae; they may b§ detected by a clear, oval 
space on the npper side; on laying this open, a large cap- 
sule will be discovered; inside of this capsule is a project- 
ing ridge covered with fine hairs, each of which contains a 
cxp 
Fig. 99. -—B, third raaxillipede; cxp. coxopodite; hp, basipodite; ip, ischiopodite ; 
m_p, meropodite; cp, oarpopodite; pp, propodile; dp, dactylopodite; c, mul* 
tiarticulate extremity of exopodite or palpus; flah, epipodite or flabellum. 
minute branch of the auditory nerve. The sac is filled 
with water, in which are suspended grains of sand which 
find their way into the capsule. A wave of sound disturbs 
the grains of sand, the vibrations affect the sensitive hairs, 
and thus the impression of a sound is telegraphed along 
the main auditory nerve to the brain. 
The fine hairs fringing the mouth-parts and legs are 
organs of touch. The seat of the sense of smell in the 
Crustacea is not yet known, but it must be well developed, 
as nearly all Crustacea are scavengers, living on decaying 
