57^.05+2- 
MONTHLY MICROSCOPICAL JOURNAL. 
JULY 1, 1876. 
I. — On the Rotifer Conochilus volvox. 
By Henry Davis, F.K.M.S. 
(Bead before the Koyal Microscopical Society, June 7, 1876.) 
Plate CXLIII. 
Few microscopic objects have been so much gazed at during the 
last dozen years as Conochilus volvox ; scarcely a single scientific 
soiree, where the microscope has figured, has failed in a supply of 
their living crystal spheres ; yet it would be difficult to mention a 
minute creature of any attractiveness which has been so little 
studied and is so little known. It is the object of the present 
paper, in part, to supply the omission, and to piece together, in a 
manner as disjointed as may be, the notes made on this beautiful 
rotifer, at somewhat wide intervals during the last seven years. 
My early gatherings were made at Hampstead Heath in 1868, 
but lately this locality has failed me, and by the assistance of my 
friend, Mr. F. Oxley (who is the best collector I know), a fairly 
continuous supply has been kept up, mainly from the ponds about 
Snaresbrook. Now a careful scrutiny of the very first gathering 
revealed the fact that, judged by the rules of symmetry as applied 
to the Melicertans (among which, latter-day observers class Cono- 
chilus), this rotifer has its leading features entirely dislocated. 
The most striking peculiarities are found in and about the head ; 
but before going into particulars, it may be well to note what 
authority says about it. Ehrenberg tells us : " The frontal region 
EXPLANATION OF PLATE CXLIII. 
Fig. 1. — Diagram sketch of head of a Melicertan (Limiiias). 
A. Aperture of mouth outside the disk. 
„ 2. — Diagram sketch of head of female Conochilus. 
A. Aperture of mouth inside the disk. 
,, 3. — Group of Conochilus volvox (female), x about 300. 
„ 4. — Male „ (male) „ „ 
„ 5.— Egg of male „ .... „ „ 
„ 6. — ,, female .... „ „ 
„ 7.— Ephippial egg „ .... „ 750. 
VOL. XVI. B 
