Herkiott. — Occurrence and Habits of Lepidurus viridis. 



289 



Size. 



The sizes varied considerably also. In the following measurements the 

 total length has been taken from the front ridge of the head to the posterior 

 end of the caudal lamella, the caudal setae, as mentioned bef re, being 

 frequently broken or eaten off by other animals ; where these have ap- 

 parently not been injured in any way their measurements have been given 

 also. 



Linwood specimens 



Springston specimens 



Ashburton specimens 

 Cashmere specimens 



ECDYSIS. 



Another interesting performance of which some notes were taken was 

 the process of ecdysis, or moulting. As mentioned above, several cast shells 

 were found on certain mornings, the process of casting them having taken 

 place, as is usual in such cases, during the night. One morning, however. 

 a small pale-coloured animal was discovered to be just in the act of casting 

 its exoskeleton, and a close watch was kept. When first noticed it had 

 freed the posterior portion of the body from the old shell, including ten 

 body-segments, the caudal lamella, and the caudal setae, and was then 

 busily engaged in the task of freeing its sixty-odd pairs of limbs. The 

 caudal setae were bent, and appeared to be attached to the lamella. The 

 segments were pale grey in colour, with lighter markings at the division 

 of the segments. The exoskeleton had apparently been torn just about the 

 level of the seventh segment to allow these parts to be drawn out. 



At first the animal was very active. Lying on its back, it moved the 

 appendages one after another, beginning with those at the posterior end. 

 After a minute or two of these movements it would jerk the body violently, 

 at the same time moving the tail portion very rapidly round and round. 

 Then the first position was resumed, and again the jerking and twisting 

 followed. The animal seemed to be endeavouring to free its body from 

 the exoskeleton by its series of movements, and apparently tested the 

 results at intervals in its violent struggles to draw some of its limbs 

 out of their covering. While it was watched it made some progress. As 

 far as could be seen with the aid of a magnifying-glass, all the limbs were 



10— Trans. 



