Professor G. O. Sars, of Christiania, has made some exceedingly interesting experiments, whereby he has succeeded in hatching artificially and domesticating in his aquarium various Australian fresh-water Entomostraca. The materials for these experiments consisted of small quantities of mud taken from the bottom of lakes and small fresh-water ponds near Rockhampton. After being thoroughly dried, I forwarded this mud to Christiania. The specimens sent looked on their arrival like small masses of rock, and were so hard that they could scarcely be broken with a hammer. Nevertheless they contained living germs in the form of eggs, which had been deposited by entomostraca living in the waters in question. In most cases these eggs proved to be encased in peculiar capsules, which frequently bore a startling resemblance to bean-pods, and in some of the specimens they were found in great numbers. By softening the mud and by a suitable preparation in aquaria, Professor Sars succeeded not only in producing perfectly developed individuals, but also in getting them to propagate in the aquaria, and thus it became possible to make very exhaustive investigations in regard to a portion of Australia’s fauna hitherto almost entirely unknown. One of the most striking forms hatched in this manner is the little Daphnia called D. lumholtzii.
EGG OF Daphnia lumholtzii.
Daphnia lumholtzii.
In addition to this, nine others have been described by Professor Sars in two treatises: “On some Australian Cladocera raised from dried mud,” Christiania Videnskabs-selskabs Forhandlinger, 1885; and “Additional Notes on Australian Cladocera,” Christiania Videnskabs-selskabs Forhandlinger, 1888. On the same subject he has recently published a treatise: “On Cyclestheria hislopi (Baird), a new generic type of bivalve Phyllopoda, Christiania Videnskabs-selskabs Forhandlinger, 1887,” in which he has described a most interesting animal form, which the author hatched in the same manner, and observed through several generations. This animal has been noted heretofore in specimens from India and Ceylon, but very imperfectly, and hence mistakes have been made in regard to its systematic position, and no knowledge was obtained as to its interesting habits and life. It belongs to the so-called shell-covered phyllopoda, of which only a limited number of species have hitherto been known. One of its chief characteristics is the fact that it is enclosed in a transparent double shell, which has a deceptive likeness to a clam-shell. The anatomical examination of the animal has demonstrated that it cannot be classified with any of the known genera, but forms the type for a new one, to which the name cyclestheria has been affixed. In regard to propagation and development, this form differs widely from all the phyllopoda heretofore known. Contrary to the general rule, the eggs are developed within the shell of the mother animal, and this development is direct, not through any metamorphosis, as is the case with the other known Phyllopoda. In his treatise Professor Sars has given the whole history of the development of this animal, which abounds in interesting facts.
Cyclestheria hislopi.
