1889.] ON SOME PRESHWATER OSTRACODA AND COPEPODA. 39 



cies reappeared the following summer 1887 in considerable num- 

 ber ami continued to live and propagate during the whole re- 

 maining put of the year. In order to see, how far into the 

 winter they would endure, I did not allow the water te evaporate 

 in this aquary, but ponied on it from time to time fresh water. 

 In fact the specimens continued to live also in the new year 

 1888, though their activity was considerably diminished in the 

 same proportion as the temperature became lower. Still in the 

 beginning of March there were numerous specimens present in 

 the aquary, both adult and young, but in the course of that month 

 a great mortality began to affect the species, numerous specimens 

 h,!, ' M " t ' ,,|l " | l al the bottom dead or in a very morbid state, with 

 the valves wide open. This was, I believe, for a great part 

 caused by the water having assumed too much condensity by 

 evaporation. In fact after having supplied to the aquary a new 

 quantity of fresh spring water, I found that the remaining spe- 

 cimens became rather more active, as also that the hatching 

 of the young was going on, in spite of the comparatively low 

 temperature. In May the water of the aquary had assumed a 

 •'ather impure appearance, being very turbid and af a greenish 

 colour, owing to great quantities of microscopical alg* having de- 

 veloped. As this condition of (lie water seemed highly to altect 



bottom, I thought it right to empty the aquary at once and 

 POUT tiesh spring water on the bottom residue. This done, 



exposed to the direct, rays of the sun The result was very 

 satisfactory. During the following month, besides numerous young 

 recently hatched, also several full-grown specimens, which had 



to be i n very good health) deposit i ng their ova on the bottom 

 and to the walls of the aquary. The number of specimens 



astonishing, and at last the aquary literally swarmed with 

 enormous multitudes of this form. The species has continued 

 '" Kve in the aquary until the moment, 1 write these lines 



