444 
Transactions of the Society. 
IX. — On Floscularia pelagica sp. n., and Notes on several other 
Rotifers. 
By Charles F. Bousselet, F.R.M.S. 
{Read June 21 st, 1893.) 
Plate VII. 
When Dr. Hudson established the Botatorian order of Rhizota (tlie 
rooted, fixed when adult) it seemed to be such a well-defined group, 
with all its members permanently fixed to plants or submerged objects, 
except Conochilus Volvox , in which the animals of the colony are 
attached to each other in a common gelatinous envelope, and excepting 
also the very aberrant genus Trochosphsera. But before having 
completed his great work, Dr. Hudson had to describe a Conochilus 
( C . dossuaris) not fixed, nor aggregated together in colonies, but 
swimming about solitarily in his tube, and a free-swimming Floscule 
(F. mutabilis) which he called at the time “ a horror to every 
classifier.” Since then, Mr. Western has found a free-swimming 
Lacinularia, and Surgeon Gunson Thorpe, R.N., has just described a 
free-swimming Megalotrocha and another free Lacinularia , so that 
both families of the Rhizota furnish us at present with examples of 
animals that are not rooted or fixed when adult. 
To these I have now to add another Floscule having a corona of 
vibratile cilia in addition to five tufts of stiff setae, and living in the 
open waters of lakes, which is as much a free swimmer as the 
Asplanchnae, Anuraeae, and Polyarthrae, amongst which it sails 
steadily and deliberately, carrying its narrow gelatinous tube with it. 
Floscularia pelagica sp. n. PI. VII. fig. 1. 
Specific characters : Corona circular without any lobes, furnished 
with a wreath of vibratile cilia ; within this five fleshy prominences 
with short, stiff, radiating setae ; free- swimming ; eyes absent in adult ; 
gelatinous case hyaline, very narrow and elongated. 
EXPLANATION OF PLATE VII. 
Fig. 1 a.— Floscularia 'pelagica, in tube, ventral view. 
„ lb. „ corona. 
„ 1 c. „ dorso-ventral optical section through anterior part of 
body, a, dorsal antenna. 
„ 1 d. „ male. 
„ 2 a. — Colurus cristatus, dorsal view. 
„ 2 b. „ side view. 
,, 3 a. — Notops pygmeeus, side view. 
„ 3 b. „ dorsal view. 
„ 3 c. „ jaws, front view. 
„ 3 d. „ jaws, side view. 
„ 4 a. — CEcistes brevis , ventral view. 
„ 4 b. „ anterior part of body, side view. 
