the tail. — The colour of the male is generally a bright orange, 

 less diluted than in equal-sized female specimens. 



Biological Observations. — On the 3rd July 1886 I first no- 

 ticed the presence of this form in one of my aquaries, prepared 

 on the 11th of the preceding month. By a mere chance I caught 

 a specimen with the dipping tube when searching for other En- 

 tomostraca. On closer examination I convinced myself that the 

 aquary contained several specimens of this form; and subse- 

 quently too in another aquary prepared somewhat earlier with 

 mud from the same locality, this form was found to have deve- 

 loped. Finally, in a third aquary, prepared on the 9th June 

 with mud from another locality, the same species was hatched 

 and successfully domesticated. It was not easy however to ob- 

 serve the animals in the aquaries, owing to their peculiar habits, 

 mostly hiding, like other species of the genus, in the bottom- 

 deposit. The specimens were then rather small, though partly 

 ovigerous, and had as yet no lines of growth on their carapaces. 

 They however rapidly increased in size and multiplied prodigi- 

 ous^, so that the bottom of these 3 aquaries, after the lapse of 

 some time, literally swarmed with specimens, young and adult. 

 Some of the specimens now showed distinct lines of growth and 

 the number of these lines continued successively to increase, ac- 

 cording as the specimens increased in size. On examining one 

 of the aquaries after my return from an excursion in the begin- 

 ning of September, I still found numerous specimens at the bottom, 

 and now most of them had their shell surrounded by a thick 

 crust of ferruginous matter derived from the bottom-material. 

 This crust having been removed by the aid of a soft brush, the" 

 larger specimens exhibited a rather bright reddish colour and 

 showed numerous lines of growth. Some of them had their in- 

 cubatory cavity filled with ova of a very dark opaque appear- 

 ance, which indicated their character as true winter-eggs. Of 

 any ephippial structure on the dorsal part of the carapace there 

 was no trace however to be detected, and this I have also found 

 is the case with our indigenous species, the whole carapace serv- 

 ing, after the death of the specimen, as an envelope for the ova. 



