702 
Transactions of the Society . 
posterior tapering and obtusely pointed, tbe lateral margins flattened 
and nearly parallel ; dorsal surface rounded, tbe ventral plane ; lip 
narrow, inconspicuous ; frontal and ventral styles five, scattered ; anal 
styles five, all projecting beyond tbe posterior margin, tbeir extremities 
usually fimbriated ; marginal styles uninterrupted, long and conspi- 
cuous ; dorsal, bispid setae long and prominent ; peristome field small, 
obovate, somewhat remote from tbe frontal margin, tbe inner or right- 
band border apparently bearing a pendent membrane ; nucleus double ; 
contractile vesicle single, spherical, situated near tbe centre of tbe left- 
hand body margin, between the nuclear nodules. Length of tbe body 
1/500 in. Hab. standing pond water. 
Oxytricha ludibunda. Fig. 11. 
Body ovate, depressed, soft and flexible, less than three times as 
long as broad, widest and rounded posteriorly, tapering toward tbe 
rounded anterior extremity, tbe right-band border somewhat flattened, 
tbe left-hand margin convex ; peristomial field narrow, scarcely arcuate, 
tbe right-hand or reflected border ciliate and bearing a membrane ; 
frontal styles about eight, tbe three posterior smallest and most 
setose ; ventral setae five in number, two situated near tbe posterior 
termination of tbe peristome field, one subcentrally placed on tbe 
ventral surface, and two in close proximity to tbe five anal styles, tbe 
last often fimbriated ; marginal setae largest and most conspicuous 
at tbe posterior border ; nuclei two, ovate ; contractile vesicle single, 
spherical, near tbe centre of the left-hand body margin. Length of 
the body 1/245 in. Hab. standing pond water with decaying 
Sphagnum. Movements rapid and erratic. 
Histrio Sphagni. Figs. 12 and 13. 
Body obovate, depressed, about twice as long as broad ; posterior 
extremity rounded, narrower than tbe anterior, tbe latter obliquely 
truncate at tbe left-hand side ; upper lip small, crescentic ; right-hand 
lateral border convex, tbe left-hand margin somewhat flattened, often 
sub-centrally concave or broadly emarginate ; peristomial field broadly 
obovate, tbe posterior apex directed toward the right-hand side, tbe 
right-hand border finely ciliated and bearing a membrane; frontal 
styles nine, tbe three most posterior smallest and most setose ; ventral 
styles five, two anteriorly, one sub-centrally, two posteriorly placed ; 
anal styles large, only tbe first and the second on the right- 
hand side projecting beyond tbe posterior body margin, tbe extremities 
of all usually fimbriated ; marginal setse uninterrupted, those on tbe 
posterior margin largest ; contractile vesicle single, spherical, on tbe 
left-hand side near tbe apex of tbe peristome field. Length of body 
1 /1225 in. Hab. standing water, with decaying Sphagnum. 
Fig. 13 shows a diagram in outline of the left-hand body margin 
