280 DR. WEISSE, ON FLOSCULARIA ORNATA. 
following day (the 18th), early in the morning, he perceived 
in this egg two distinct bright-red eye-spots, which, owing 
to the visible movements of the already developed embryo, 
were continually changing their relative positions towards 
each other ; and, at the same time, he noticed a faint ciliary 
movement at one end of the embryo young floscularia, 
in this condition, since none is given by Ehrenberg, 
who had only obtained a sight of the embryo by artificially 
rupturing the egg. 
Whilst his whole attention was directed to this ovum, 
two others in the meanwhile had so far advanced in their 
development that the eggs were already visible in them. 
They both gave exit to the embryos on the 22nd, one at 
eight o’clock in the morning, and the other two hours later ; 
in both the ciliary movements, at the anterior end, were 
distinctly visible whilst the embryos were still within the 
shell. In a fourth egg the embryo had died, as was evident 
from the circumstance that its contents, even before the 
appearance of the eye-spots, had contracted from each end 
into the middle of the egg into an irregular mass. The fifth 
egg, lastly, that, viz., which the author had seen escape from 
the parent on the 16th, presented as early as on the 20th, 
in the morning, both eyes in the actively moving embryo, 
but it did not rupture before the morning of the 23rd, so 
that the complete development of the embryo was effected 
within seven days. In conclusion, he remarks that the first 
egg had probably been deposited on the 13th August. 
The foregoing observation stands in striking contrast to 
Ehrenberg’s statements respecting the rapid propagation of 
Hydatina senta.* But, since, from the author’s previous 
researches,t as well as from many later observations on the 
subject of the ova of the Rotatoria, it is evident that their de- 
velopment proceeds with tolerable slowness, Hydatina senta 
must probably be regarded as an exception to the general 
rule. 
Lastly, the author cannot refrain from adverting to the 
erroneous statements of M. Pesty respecting Floscularia. 
That writer, at p. 47 of his ‘Memoir on the Knowledge of 
the Smallest Living Forms’ (1852), states, “ At the foot 2—3 
ova, each two thirds as big as the body of the parent animal. 
Vitellus brown, and set round with short hairs,’ &c. But 
the eggs of this Rotifer are so small as hardly to equal 
* ‘Zur Erkenntniss der Organisation in der Richtung des Kleinsten 
Raumes.’ 2nd part, 1832. “2 
+ “Zur Oologie der Raderthiere.” In ‘Mémoires de l’Académie impé- 
riale des Sciences de St. Petersbourg,’ VII série, tome iv, 1862. 
