ANATOMY OF THE LOBSTER. 271 
Though as many images may be formed in each eye as there 
are distinct crystalline cones, yet, as in man with his two 
eyes, the effect upon the lobster’s mind is probably that of 
a single image. 
The lobster’s ears are seated in the base of the smaller or 
first antenne ; they may be detected by a clear, oval space 
on the upper side ; on laying this open, a large capsule will 
be discovered ; inside of this capsule is a projecting ridge 
covered with fine hairs, each of which contains a 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 audi- 
tory nerve to the brain. 
Organs of touch are the fine hairs fringing the mouth- 
parts and legs. The seat of the sense of smell in the Crus- 
tacea is not yet known, but it must be well developed, as: 
nearly all Crustacea are scavengers, living on decaying mat- 
ter. Crabs also have the power of finding their way back to 
their original habitat when carried off even for several miles. 
The two large so-called ‘“‘ green glands” situated on each 
side within the head-thorax, and having an outlet at the 
base of each of the larger antenne, are probably renal in 
their functions, corresponding to the kidneys of the verte- 
brate animals. The shell glands are of the same nature. 
The ovaries and corresponding male glands, are volumi- 
nous organs, the testes being white, and the ovaries, when the 
lobster is about to spawn, being highly colored, usually pale 
green, and the ovarian eggs are quite distinct. The lobster 
spawns from March till November; the young are hatched 
with much of the form of the adult, not passing through a. 
metamorphosis, as in most shrimps and crabs. They swim. 
near the surface until about one inch long, when they re- 
main at or near the bottom. 
The lobster probably moults but once annually, during the. 
warmer part of the year, after having nearly attained its: 
maturity, and when about to moult, or cast its tegument, the- 
carapace splits from its hind edge as far as the base of the: 
