156 CRUSTACEA——-EUCARIDA—DECAPODA CHAP. 
breaking joint, the animal forgets to throw the injured leg or 
stump off at the breaking joint, a proceeding which always 
occurs under normal conditions. The regeneration of a limb 
starts from a papilla which grows out of the breaking-joint, and 
after a number of moults acquires the specific form of the limb 
that has been lost. A number of interesting observations have 
been made upon the regeneration of the limbs in Crustacea, It 
was in the Hermit-crab that Morgan! proved that regeneration 
and the lability to imjury do not always run _ parallel, as 
Weismann held they should, since the rudimentary posterior 
thoracic limbs, which are never injured in nature, can regenerate 
when artificially removed as easily as any others. Przibram * 
has shown that in the shrimp Alpheus, whose chelipedes are 
highly asymmetrical, if the large one be cut off, the small one 
immediately begins to grow and to take on the form of the 
large one, while the regenerated limb is formed as the small 
variety. This remarkable inversion in the symmetry of the 
animal clearly ensures that, if the large chela is injured and 
thrown away, the least amount of time is wasted in providing 
the shrimp with a new large claw. 
To return to the Lobster; for the majority of the individuals 
there is a definite breeding season, viz. July and August, but a 
certain proportion breed earlier or later. A female begins to 
“berry” at about eight inches in length, and to produce more 
and more eggs up to about eighteen inches, when as many as 
160,000 eggs are produced at a time; after this there is a 
decline in numbers. A female normally breeds only once in two 
years. Strict laws are enforced forbidding the sale of Lobsters 
and Crabs “in berry” in both England and America. The 
period of incubation, during which the developing eggs are 
attached to the swimmerets of the female, lasts about ten or eleven 
months, so that the larvae are hatched out approximately in the 
following June. On hatching, the larva, which measures about 
one-third of an inch, and is in the Mysis stage (7.e. it possesses all 
the thoracic limbs in a biramous condition, but is without the 
abdominal limbs), swims at first on the surface. After five or six 
months of this life, during which the abdominal pleopods are 
added from before backwards, it sinks to the bottom, loses the 
1 Zool. Bulletin, i., 1898, p. 287. 
2 Archiv fiir Entw. Mech. xi., 1901, p. 321. 
