372 Proceedings of the Bayed Physical Society. 



reproduced in the time intervening between one moult and 

 the next. " Les autres merabres, tels que grosses pattes, 

 petites pattes, fausses pattes et lamelles de la queue, se 

 regenerent plus lentement, trois nines ayant lieu durant leur 

 regeneration. Lorsque survient la quatrieme mue les membres 

 regeneres ont toute leur force." It appears also from his 

 observations that adult females moult only once a year, 

 while adult males undergo two ecdyses in the same time. 

 It thus happens that new limbs in the male attain their full 

 development in one and a half to two years, while in the 

 female a similar reproduction extends over three or four 

 years. 



Huxley, in his work on the Crayfish (7), gives a resume 

 of our knowledge of the subject, so far as that form is con- 

 cerned. His account is mainly a summary of Eeaumur's 

 observations ; there is, however, one point of difference which 

 is worthy of note. After describing the formation of the 

 new limb as a bud enclosed within its thin cuticle, Huxley 

 adds: ''At the next ecdysis the covering cuticle is thrown 

 off along with the rest of the exo- skeleton ; while the rudi- 

 mentary limb straightens out, and though very small, acquires 

 all the organisation appropriate to that limb." 



The histological changes connected with the process of 

 ecdysis have been carefully studied by Max Braun (6) and 

 Vitzou (8) ; but I do not propose to discuss this portion of 

 the subject here. 



My own observations were commenced in the autumn of 

 1882, and extended over a period of nearly three years. The 

 specimens were kept under observation in my Aquarium at 

 Huddersfield. Attention was paid especially to the rate of 

 reproduction of lost limbs, and to the increase in size which 

 takes place with each ecdysis. The specimens under ob- 

 servation will be referred to as A, B, and C. All three were 

 received from Jersey on the 2d October 1882. 



A. was a female, measuring about 8^ in. in length (tip of rostrum to end 



of telson). 



B. measured, previous to ecdysis of 19, v. 83, 7| in., and was a male. 



C. was nearly 7 in. long previous to ecdysis of 1, vii. 83, and was also a 



male. 



