222 Transactions of the Royal Microscopical Society. 
bricklayer smooths over his stucco with his flat trowel ; and I have 
very little doubt that L. annulatus does much the same with its 
remarkable instrument. M. ringens has nothing like an operculum, 
but its analogous organs, namely the hooks and the pimple of setae, 
also in my opinion serve a double purpose, and are used for defence 
and building ; for the two hooks are formidable weapons at close 
quarters when the animal finds a disagreeable opponent intruding 
into its case. The recognition by Dr. Hudson of the striking 
form Melicerta tyro, is also most acceptable. The presence of the 
third pimple of setae in that form, the absence of the hooks, and of 
the pellet organ, and the presence of the long antennae is cer- 
tainly very instructive. As to the so-called M. pilula, I am sorry 
Mr. Cubitt did not alter that name when he was altering that of 
L. annulatus, and bring the animal down to a Limnias. M. pilula, 
so far as its building habits go, starts off in a widely divergent 
line of its own ; for it makes its pellets in its stomach, and builds a 
house of ejectamenta ; and as Dr. Hudson says of M. tyro, it is 
another delightful instance of how Nature seems to utterly baffle us 
when we attempt to generalize — for while it comes close up to 
Limnias in its form (except that it wants the shield-like addition), 
and while it has the two antennas of a Melicerta, yet it makes its 
case in a new and wholly unexpected manner, and differently from 
either of them. The pimple of setae which M. ringens carries 
between the hooks, and to which I have drawn attention above, 
will at once remind the observer of the so-called siphon of Cephalo- 
siphon which springs from the same spot, as also of the antennae of 
Philodina and Rotifer vulgaris. 
I may be unduly prejudiced in favour of my subject, but the 
apparatus of M. ringens always fills me with wonder and delight ; 
it stands in my judgment so completely and instructively per se, 
it is so complicated yet so accurate in its performance, the apparent 
intelligence of this “ speck of life ” is so extraordinary, the results 
are so unexpected, so many points too of the animal’s economy have 
to be considered in estimating the final result ; and although true 
it is that we have, even from Stentor upwards, a series of rough 
building processes going on, which result in more or less workman- 
like habitations, yet the leap from the very best of them (Limnias) up 
to M. ringens is to my mind a vast, a giant stride, and just as great 
as the step from a lath-and-plaster cottage up to a house built of 
patent stone, made by the aggregation of sifted sand forced together 
in a mould and deposited by the action of highly complicated ma- 
chinery. To start from Limnias and reach by development an animal 
which in the size of the tenth of an inch shall make 1000 separate 
bricks, each brick shaped like a rifle bullet, convert a sphere into a 
complicated figure, turn the brick round, lay it in its right place and 
attitude, make another, lay that next it, throw away its waste material, 
