4 G. ©. Sars. 
brown sand, without any mud intermingled, and at first I 
therefore had some doubts as to the suitableness of such a 
material for hatching operations. On a preliminary micro- 
scopical examination of the sand, however, some scattered 
pieces of the carapace of an Apus, and of the shell of a 
bivalve Phyllopod were easily detected, as also a few 
detached valves of 2 different Cypridids, and this induced 
me immediately to start upon my hatching experiments. 
For this purpose I prepared a series of aquaria, to receive 
each a small portion of the sample, the date of preparation 
being in each case noted. The aquaria were placed in my 
laboratory in such a manner, that they were exposed to the 
direct rays of the sun during the first part of the forenoon, 
and in clear weather the temperature of the water was 
often found during this time to rise to a very considerable 
height. After the lapse of some days a few small Ento- 
mostraca made their appearance in a number of my aquaria, 
whereas in others no trace of life could be detected, either 
at that time or subsequently. The latter were of course 
discarded, while the former were kept for further observation 
during the whole summer. Of the results of my experi- 
ments, which I believe may be of some interest, I propose 
to treat in the present paper. The number of species 
hatched and examined in detail, is rather limited, amounting 
to only 5 in all, viz, 2 Phyllopoda, 1 Cladoceran, and 2 
Ostracoda; but of these only one of the Phyllopoda seems 
to have been noticed at an earlier date, whereas I regard 
the 4 other species as new to science. 
