Tue Microscope. 103 
ness of his interpretation that he figures one of these organs. 
It has been said, however, that this fimbriated aspect is prob- 
ably an optical illusion due to the rapid vibrations of two con- 
centric ciliary circles. Sterki’s observations are somewhat 
incomplete if the species I have is identical, as I suppose, with 
his Tintinnidium conciliatum, yet he is not the victim of an 
illusion; there is but a single row of these adoral cilia, and they 
are distinctly fimbriated distally, not, indeed, as his figures 
seem to indicate, with rigid teeth, but with fine, flexible fila- 
ments of great delicacy. In several instances I have observed 
cilia with one or more filaments thrown into a loop, as in 
Figure 1, 
With my specimens the peristome border encloses the inner 
series of short, simple cilia, as well as the vibrating tongue-like 
projection, mentioned by Sterki, and the outer wall of the oval 
cleft is itself ciliated, a structural feature not before noticed. 
The peristome border bears externally numerous sete arranged 
in perpendicular, equidistant rows of four or five bristles each, 
and a single, obliquely directed anterior series of twelve or fif- 
teen. These become conspicuous as the animalcule, when ex- 
tended and undergoing reproductive fission, continually and 
slowly rotates, thus bringing each series successively into focus. 
How this movement is accomplished without perceptible twist- 
