VI MACRURA—NEPHROPSIDEA—-LOBSTER 155 
dangerous one to the Lobster and to Crustacea in general, and is 
very frequently fatal. There is, first of all, the danger of the act 
not being accomplished skilfully, when death always ensues. 
The Lobster remains soft and unprotected for about six weeks 
after the ecdysis, and is very apt to fall a prey to the predaceous 
fish, such as Sharks, Skates, Cod, ete, which feed upon it. 
There are, however, some peculiar adaptations connected with the 
process which are of interest. In order to facilitate the ecdysis, 
areas of absorption are formed upon the dorsal and ventral 
surfaces of the carapace, on the narrower parts of the chelipedes, 
and at other places; in these areas the calcium carbonate is 
absorbed, and the old shell becomes elastic and thin, so as: to 
allow a more easy escape for the moulting Lobster. It has been 
noticed that while this is taking place large concretions of 
calcium carbonate are formed at the sides of the stomach, known 
as “ gastroliths,” which perhaps represent the waste lime that 
has been abstracted from the areas of absorption. After 
moulting the Lobster is in great need of lime for stiffening his 
shell, and it has been noticed that on these occasions he is very 
greedy of this substance, even devouring his own cast-off skin. 
The male Lobster is especially prized on acceunt of his 
larger chelae, but in both sexes the chelipedes are differentiated 
into a smaller cutting pincer and a larger crushing one. Lobsters 
may be right or left handed, with the large crushing claw on the 
right or left hand, and sometimes specimens occur with the 
smaller cutting pincers on both chelipedes, and very rarely, 
indeed, with crushing claws on both sides. Crustacea very 
commonly have the power of casting off a limb if they are 
seized by it or if it is injured, and of regenerating a new one. 
In the Lobster a so-called breaking-joint is situated on each leg 
at the suture between the fused second and third segments ; 
a membrane being pushed inwards from the skin, which not 
only serves to form a weak joint where rupture may easily take 
place, but also to stop excessive bleeding after rupture. In the 
newly-hatched larvae there is a normal joint between the second 
and third segments; and autotomy, or the voluntary throwing away 
of a limb, never occurs until the fourth larval stage, when the 
breaking joint is formed. Autotomy is a reflex act under the 
control of the segmental ganglion; if a Crab or Lobster be 
ansthetised, and then a limb be injured or broken off below the 
