NOTES ON SOME FREE-SWIMMING ROTIFERS. 235 
extended acquaintance with it, I also came to the same conclusion, 
we named it Zriarthra breviseta (Gosse). MJonocerca has a styli- 
form foot, but in this animal the appendage has none of the 
characters of a foot. Then, too, the numerous muscles, and long 
curved sesophageal tube point to the genus Zriarthra. The dis- 
coverer’s description is very short, and I am not aware that any 
microscopist has since come across the animal. It may be watched 
for a considerable time without showing the least trace of the 
anterior spines, and then all at once it may retract the ciliary 
region, when the spines, which are about one-fourth the length 
of the animal, will be thrown up. Fig. 26a, large specimen 
swimming; 4, smaller one beginning to retract its cilia, showing 
anterior spines just leaving its sides ; ¢, another small one, with cilia 
completely retracted, and spines erected. Fig. 27, /Furcularia 
Jorficula. Characters, cylindrico-conical; obtusely pointed in front; 
foot, short, cylindrical ; toes, long, stout, recurved and dentate 
(not at the base, but about the middle); one eye, frontal; cilia 
covering anterior pointed region; internal organs, as figured. 
According to Perty this Rotifer differs from Déstemma forficula 
only in its single frontal eye, Dzstemma having two, cervical. My 
specimens did not agree in several points with the description of 
either the two animals named. The point, however, to which I 
wish to draw particular attention is the following, viz., its possession 
of two zzternal spines. The animal suddenly draws in its anterior 
part, and the two internal spines are thrown out laterally, the 
points pressing out the integument quite away from the internal 
organs. I have never satisfactorily made out the point of attach- 
ment of these spines, but several circumstances seem to indicate 
that they arise dorsally, and not far from the base of the foot. 
Several specimens I had on a glass slip frequently went through 
the performance mentioned, so that I never had any difficulty in 
seeing the spines. Mr. Bolton, however, writes me to say that he 
has not been able to satisfy himself about them. No Rotifer, so 
far as I am aware, has ever been described with such a peculiarity, 
and I shall be extremely pleased if other microscopists can confirm 
my observations. It would also be interesting to know if Déstemma 
forficula is possessed of these spines. Fig. 28 is another Rotifer 
of the same genus as the last. I merely figure it to show that in all 
my specimens the toes get broader towards the free end. I have also 
come across another Rotifer similar to the last, but smaller, and 
with longer toes, which is characterised by the same peculiarity. 
As this is so different to the stereotyped toe I shal] be glad to hear 
if others have noticed such a departure from the usual type. 
Fig. 29 is a charming Rotifer found upon decaying leaflets of 
Myriophyllum at the bottom of one of my aquaria. I am not aware 
of having seen it before, although I am a Microscopist of about 15 
