266 
MICROSCOPIC POND-LIFE. 
Dec., 1892. 
Some few years ago, when I was hunting for “ Collared 
Monads ” with a high power objective, I came across some 
Actinosphaeria possessing a curious case or shell. As may be 
seen by comparing the scales of magnification of the two dia¬ 
grams (Plate VIII.), it is considerably smaller than the common 
Actinosphaerium. It is less than T woo °* an i n diameter, 
while a very small Actinosphserium is at least xnoo or " an i n °h 
across. Its method of reproduction is the same as that of the 
Actinosphserium ; but in that creature, as soon as a new one 
is formed, it splits off and forms a separate animal. The 
shell or skeleton of this creature retards complete separation, 
and I saw some specimens with only one animalcule in a 
shell, and which looked, save for the shell, like the common 
Actinosphserium. Some specimens had two in a shell ; 
others three ; others four, as in the figure ; while a few shells 
contained five or six animalcules. The rays or hairs came 
through little warts in the shell, and these warts were 
every here and there prolonged into tubes, as shown 
in the drawing. It seems to me that what I found 
is practically a freshwater foraminifer. Perhaps it has 
been seen before, perhaps not. At any rate it seems very 
scarce at Oxford, for I have never seen it before or since. 
But it might be easily overlooked on account of its small 
size, for it is by no means as conspicuous as the common 
Actinosphserium, large specimens of which are a hundredth 
of an inch or more in diameter. But, whether or no it is a 
“new species,” it is very interesting as showing that the 
lowly amoeba-forms of life have hard parts or skeletons in 
freshwater as well as in the sea. As for the texture of the 
shell, it is quite transparent and very fragile compared with 
the shell of a foraminifer, just as the shells of freshwater 
mollusca are much more fragile than sea-shells. I think that 
the figure that I have given will enable anyone reading this 
who meets with specimens of it to recognise it. 
I cannot very well reproduce my lecture here without a 
number of figures, which I have no time to draw, and which 
the editor would not care to print. But I should like to point 
out that every class of the lowly animals known as Infusoria 
gives us some individuals possessing hard parts or skeletons, 
and some individuals without them. In the Monads, if we 
place them next above Amoebae in the scale, we find, for 
example, the genus Salpingoeca (Pitcher-dwellers), with a 
skeleton, and Codosiga (Silent Bell) without. Monads have 
no mouths, but they eat only at one part of their body, and 
not all over it as do Amoebse. The well-known Vorticellidae 
have a distinct mouth, but no digestive organs. A large 
