PEOTOZOA OF HEETFOEDSHIEE. 
99 
to undue pressure, they throw out a film of sarcode, giving the 
appearance of a delicate sheath or lorica, and ultimately withdraw 
the collar and flagellum; hut when the pressure is removed, the 
normal condition is gradually resumed. 
The next genus is called Astrosiga , and is limited to a single 
species. The animalcules, as the name implies, are united in stellate 
clusters of about five monads, swimming freely in the manner of 
Uvella. It does not appear to have ever been found in England. 
There is one other free-swimming form, which constitutes the 
next genus, Desmarella, in which the animalcules are united in 
chain-like rows, moving very rapidly through the water by the 
action of their combined flagella, rendering observation a difficult 
matter. With the exception of one species described by Stein, the 
members appear to be confined to salt-water habitats. . 
We now come to the second family, Salpixgoecid^e, in which the 
members secrete a lorica or protective case, and it is here that we 
find the greatest diversity and wealth of form. Taking first those 
species in which the pedicel is rudimentary, we have SaVpingceca 
amphoridium , in which the lorica (which is the basis of classification) 
is shaped like a Elorence flask, or water-carafe. It is by far the 
most common species of the genus. When found upon confervoid 
filaments, the animalcules are often as closely packed as are the cells 
in a beehive, and, were it not for their extreme transparency, would 
often obscure the view of their resting-place. There is a great 
tendency in these animalcules to alter their shape; the tiny speck 
of protoplasm often grows too large for its little crystal cell, and 
then bubbles out, pushing aside the collar and flagellum, which 
are often withdrawn; and the finger-like processes, which are 
sometimes assumed by the sarcode, remind one of a Difflugia. 
TJltimately, this redundant sarcode is separated from the parent 
body, floats or crawls off in the manner of an Amoeba (for which it 
might easily be mistaken if first encountered in this stage), and, 
after a short time, settles down and developes into a collared monad 
resembling the parent, which also, after fission, draws back into 
the lorica, and gradually assumes its pristine contour. 
Another very beautiful form which I have met with very fre¬ 
quently at Hertford Heath is S. fusiformis. Its exquisite vase-like 
contour must at once arrest attention. A wide departure in form is 
shown by S. ampulla , a species inhabiting salt-water, which has 
not come under my observation, but which I feel that I can hardly 
pass without notice. Here we find that part of the lorica which 
surrounds the collar inflated in a beautiful balloon-like manner, and 
marked by longitudinal sulcate ridges. 
Even more remarkable, perhaps, is another marine form, Sal- 
pingceca cornuta, in which the development of the lorica was until 
recently without parallel amongst recorded forms, being from seven 
to ten times as long as broad, and greatly resembling the curving 
horns of certain antelopes. I have recently discovered a new 
species in which an analogous growth is present. I propose to pro¬ 
visionally bestow upon it the specific name tuba , in reference to the 
