ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 413 
of the sarconema. The axonema consists of a bundle of fine fibres 
containing a necklace-like arrangement of nuclei. 
The hyalolemma of the muscle-strand is very elastic and contractile. 
When the strand functions expansion and contraction are most marked 
in the hyalolemma. Contraction is active, relaxation passive. 
The muscle-strand surrounds numerous primary, secondary, tertiary 
cross-striped fibrils, which correspond to the primitive fibrils of other 
authors. These are not artificial products, but show the same struc- 
ture as the strand. The relaxation and contraction of muscle-fibre 
is a simple mechanical process, due to the expansion and contraction of 
the muscle-strand. Narrowing and broadening are necessary and natural 
consequences ; but the proper activity is only in contraction. 
Daday does not say that all this applies to muscles which are not 
those of Ostracods, but he evidently expects to find that it is in no way 
unique. 
Red Sea Copepods.* — Dr. W. Giesbrecht describes a collection of 
Red Sea Copepods made by Dr. A. Kramer. The collection was made 
by filtering the water drawn up by the ship’s pump, and the result 
showed that this simple method may be very effective. Analysis shows 
that the Red Sea forms have closer affinities with the Indopacific than 
with the Atlantic types. Nothing decisive can be said as to a mixture 
of Mediterranean and Red Sea fauna via the Suez Canal. The new 
species described are Scolecithrix chelipes , Centropages elongatus , Schmac- 
keria salina, Monops krdmeri, and Oithona rigida. 
Postembryonal Development of Daphnids.j - — Mr. R. Lundberg has 
had the opportunity of investigating the postembryonal development of 
a Daphnid which he found in abundance at the fresh-water biological 
station at Finspong. A study of the literature of the subject shows him 
that his observations did not contain any new facts, but by a mere 
accident, he says, he obtained an opportunity to study the matter under 
very favourable circumstances, as it can hardly be doubted that all his 
specimens belong to one and the same species. However rich the 
material may be, supposing that it has been collected partly from one 
place and partly from another, the investigator can never be sure of 
getting the series of evolution clear and complete. The author’s results 
appear to be the more interesting, since, in his opinion, the neglect to 
observe the changes of form during growth is the chief cause of the con- 
fusion and doubt which exist with regard to the distinction of species 
among the Daphnid s, or, we might safely say, among the Cladocera in 
general. All transformations of Daphnids appear to tend in the same 
direction, that is to say, spines and other prominences, the so-called 
balancing organs, tend to become shortened or even to disappear in time, 
as is the case with the larval forms of other Crustacean orders. There 
is no doubt that these changes during growth are adapted to the sur- 
rounding conditions of the medium in which the animals live, and that 
they are of a certain advantage to them. The author thinks that great 
attention should be shown to the temperature of the water at the different 
depths at which the creatures are found. 
* Zool. Jahrb. (Abth. Syst.), ix. (1896) pp. 315-28 (2 pis.), 
f Bih. K. Svenska Yet. Akad. Hdlgr., xx. (1895) No. 2, 19 pp. (2 pis.). 
