10 THE ZOOLOGIST. 



in examples from a bog-pool in Scotland. There is no outer 

 cyst like that of M. dispar. The cyst formed within the moulted 

 skin resembles the inner cyst, and contains a complete animal. 

 The reduction to the simplex state has not in this instance 

 been seen. 



M. dispar is one of the few Tardigrada which have their 

 usual habitat in ponds. It is also the most boreal of known 

 species, as it was found at an elevation of several hundred feet 

 in Franz Josef Land by Mr. Bruce. Whether it is exclusively a 

 northern species remains to be seen. At present its southern 

 known limit is Scotland, but, in view of the close resemblance 

 of the adult animal to M. macronyx, I suspect that some of the 

 records made under that name really refer to M. dispar. 



In this country it lives in ponds liable to freeze in winter, 

 occasionally at the margins of lakes, and it may be that the 

 encystment is correlated with its life in permanent waters. The 

 case of M. echinogenitus, cited above, suggests the possibility 

 that species which normally live in moss may be induced to form 

 cysts when they find themselves amid the different conditions of 

 a pond. 



The publication of these observations in their incomplete 

 state is made in the hope that other students of the Tardigrada 

 may interest themselves in the " encystment," and that we may 

 thus hope for an earlier solution of the problems involved. 



Explanation of Figures (p. 5). 



1. Adult, dorsal view, showing the conical processes. 



2. Egg. 



3. Outer cyst, showing shagreened surface, and legs. 



4. Inner cyst, shown within outline of outer cyst ; dorsal view. 



5. Tooth, showing the very wide /urea. 



(All the figures are drawn to the same scale.) 



Since writing these notes I have received from Prof. Lauter- 

 born an interesting little paper, in which he describes a similar 

 encystment of Macrobiotics macronyx (Verhand. d. Deutsch. Zool. 



