94 Part L11.—Twenty-third Annual Report 
On 29th October 1904 a female cast. It had been isolated a short 
time before. It was then very limp, and half dead in appearance. It 
was swollen at the junction of the carapace with the abdomen, and some- 
what dropsical in appearance. It was not at all smart with its chele. 
Ehrenbaum says that the lobster merchant is able to distinguish a 
lobster that is about to cast, by the softening of the ventral edges of the 
carapace, 
Tue Cast SHELL. 
The colour of the dactyls of the chele is noticeable. The back edge of 
the dactyl is clean and purple in colour, and the pores are well marked. 
The cast stomach is empty. There isa glairy skin under the carapace, 
and united to the membranous lining of the integument of the abdomen. 
It ruptures easily, and is often found sticking out as a fold at the junction 
of the thorax and abdomen Vitzou, who witnessed the moulting of the 
lobster, describes this skin as a homogeneous, gelatine-like layer, which, 
under the microscope, shows no cellular structure. It is, he says, a 
secretion of the lower layers of the new carapace; it passes out by 
endosmose to lie between the old shell and the new integument. Its 
presence there facilitates the casting. 
Tue Sorr LoBster. 
The soft lobster, when just cast, is extremely soft and pliable ; the tip 
of the chela can be made to touch the telson. The stomach is full of 
little ossicles, which are derived from the breaking-up of the gastroliths. 
The lobsters at the Laboratory very often failed to rid themselves of 
their integument. A considerable number died from this cause. 
A lobster that moulted on September 22nd 1902 was kept in one of 
the compartments of a wooden hatching apparatus until October 14th 
1902. When in the wooden box it had not eaten food (fish) at all 
eagerly. It was at the latter date put into a tank, the bottom of which 
was covered with sand and gravel. It began immediately to eat small 
pebbles and gravel. Hard lobsters also have been occasionally seen 
picking up coarse gravel with the pereiopods and putting it into their 
mouths. 
When a lobster casts in a tank in which there are other lobsters it is 
usually attacked by them, sometimes before it has finished casting, and 
it is sometimes fatally injured. A soft lobster occasionally bleeds to 
death in consequence of what appear to be comparatively slight wounds. 
On July 15th a lobster was found to have lost both chelz in moulting ; 
it had been attacked and had cast off both claws. One chela was 
shrivelled just as it is when it is first withdrawn from the shell, and 
before it has swollen out. The other chela had swollen out to its full 
size. Both claws were cast off at the fracture plane. Couch observed 
that ‘“‘the rejection of the limb can be effected with the same ease 
while the crust remains soft after exuviation.” This fact militates 
against the view that strong rigid supports are necessary round the 
fracture plane to permit of the defensive mutilation on the part of the 
crustacean. 
In another case a hard lobster had lost one chela, and the other bore 
the scar of a bite. During moulting the scar prevented the withdrawal 
of this limb, so it was thrown off at the fracture plane. A bud had 
formed in place of the previously lost limb, and after the cast a diminu- 
tive chela was present; the hand (propodite and dactylopodite) measured 
24 inches long, while the normal-sized hand measures 4 to 5 inches. Brook 
