Reproduction of Lost Parts in the Lohster. 383 



The deep blue of the normal exo-skeleton is the last to ap- 

 pear. It is first seen as faint washes and patches amongst 

 the red about a month prior to ecdysis ; and before the old 

 exo-skeleton is cast, the new soft limb has become of the 

 normal deep blue colour characteristic of the living specimen. 

 The red has become entirely, or almost entirely, replaced by 

 blue. The tuberosities of the chelae, however, retain a portion 

 of the original tint. This order in the development of the 

 various shades of pigment appears to be constant in normal 

 cases. 



Rupture of the Carapace during Ecdysis. 



Although this subject does not technically come within 

 the scope of the present paper, a few notes on the process, as 

 I have observed it, may help to clear up a subject on which 

 a considerable diversity of opinion appears to exist. Without 

 reviewing the literature on the subject, which is voluminous, 

 the diversity of observation may be summed up in the 

 following question : " During ecdysis does the carapace rup- 

 ture along the median dorsal suture ? " Reaumur and a large 

 number of more recent observers assert that it does, and that 

 on this account the process of ecdysis is more easily accom- 

 plished. Others, myself included, have been unable to note 

 any rupture in the cast exo-skeleton. Under date 19, xii. 84 

 of my notes referring to Lobster C, an account will be found 

 of the condition of the exuvium after ecdysis. There was 

 no rupture of the membrane, but the cement in the dorsal 

 suture had been partially dissolved. On this account the 

 branchiostegites were allowed a certain amount of motion, 

 and as the soft parts were withdrawn, no doubt the membrane 

 lining the cephalothorax became tense to such an extent as 

 to allow the lobster to escape easily from its exuvium. But 

 it must be remembered that this specimen was by no means 

 a large one. The cephalothorax was much thinner than in 

 older specimens. Where the calcareous deposit is compara- 

 tively limited, the various portions of the cephalothorax are 

 capable of a certain amount of motion along the dorsal and 

 cervical sutures, which decreases as the shell becomes thicker. 

 Thus, in old specimens with thick shells, a rupture may be 



