FLOSCULARIA MUTABILIS. 
83 
FLO SC ULARI A M UTA BILIS. 
This very curious Floscule was discovered by Mr. Bolton 
in Olton Reservoir, near Birmingham, on August 7tli, 1884, 
and he has since found it in several other pools in the neigh¬ 
bourhood. It is remarkable for having a disc with only two 
lobes; for possessing what appear to be two eyes on the 
dorsal lobe, near its summit; and for its habit of altering 
the shape of its disc till it somewhat resembles that of an 
(Ecistes or Limnias, and then of swimming by vibrating the 
short set* that surround the edge of the disc. There is 
another two-lobed Floscule, discovered by Mr. Hood, of 
Dundee, an account of which I shall shortly publish. I 
have named it F. calva from its remarkably short set*. It does 
not, however, swim like F. mutabilis , nor does it possess red 
eyes. Oddly enough, however, it also is attached to its tube, 
and not to the stem of the alga on which the tube rests, so 
that it almost always tumbles off its perch when sent by post. 
F. mutabilis generally swims backwards, circling very 
slowly, and sure to be soon pulled up by some obstacle. Now 
and then it has a fit of energetic straight swimming, but even 
then it is usually stem foremost. It frequently shuts up its 
lobes like a puckered bag; and I have seen it often protrude 
the real mouth (which, as in all Floscules, lies deep down at 
the bottom of the “ vestibule”) right beyond the outer edge of 
the lobes. 
The young female (Fig. 8) is somewhat similar in shape to 
the adult, but has the swelling of the foot more marked. 
I have seen three specimens of what I believe to be the 
male (Fig. 4), but from my not having seen it hatched I can¬ 
not be certain. The figure shows its external shape—it was 
on each occasion too lately hatched to detect the sperm bag 
and penis : it had no teeth or alimentary tract. 
I may add that Mr. W. Dingwall, of Dundee, has sent 
me two or three specimens of a one-lobed (or rather lobeless) 
Floscule, an account of which will soon appear. There is 
now a regular series of Floscules with 7, 5, 3, 2, and 0 lobes. 
C. T. Hudson, LL.D., F.R.M.S. 
15th September, 1884. 
Fig. 1. 
n 
M 
9 9 
2 . 
3. 
4. 
PLATE I. 
Description of the Figures. 
Floscularia mutabilis (side view) at rest E \ inch. 
swimming ^ „ 
„ ,, young female ^ ,, 
,, ,, supposed male ,, 
9 9 
