4 
surrounding water where, after swimming about free for some time, it 
finally settles down on some substance and loses its cilia, and 
begins to lead a quiet immovable and undisturbed life on its own 
account. 
Sponges vary greatly in form and size from a pin’s head to 5 or 
6ft. high. Some shapes are constant and characteristic, as the 
fairy-like Venus Flower Basket, Huplectella, the glass-rope Sponge 
with its cylindrical body, Hyalonema, the open Flower Basket 
Sponge, Dactylocalyx and the Great Neptune’s Drinking Cup, 
Poterion ; but usually the shape is variable in the same species as 
we have mentioned is the case with the Bath Sponge. 
The character of the skeleton is wonderfully diverse if we 
consider the whole family of sponges, but in opposition to the 
form, is tolerably constant in the same species, and it is therefore 
taken as the basis for classification. Some sponges have no firm 
skeleton ; they are mere jelly-fish amongst Sponges, and are called 
Soft Sponges. In some, the skeleton consists of chalk spicules or 
needles of different shapes. In some of flint spicules, and in some 
of a network of horny fibres with no proper spicules. These then 
are the four great divisions of Sponges. The different spicules are 
beautiful objects for study with the Microscope. The members of 
the class with flint spicules are the most numerous, diverse and 
complicated. They are spread through all seas, at all depths, and 
all ages, being found as fossils as early as the Cambrian system. 
Amongst the species belonging to this class, is found the lovely 
object whose skeleton is known as Venus, Flower Basket. 
Euplectella, meaning a little thing beautifully woven. It has a 
framework so exquisitely beautiful in its fairy-like tracery as to 
have called forth the remark from a distinguished naturalist ‘ this 
passes the loveof woman.” Its spicules are so arranged crossing 
one another as to weave together a thin walled vase of delicate, 
very regular lattice work, with oblong meshes. The longitudiaal 
lines of the skeleton, and the transverse are remarkably regular, 
the diagonal which are applied on the surface of the others, so that 
they seem to stand out from them like delicate muslin folds, are so 
arranged that every alternate mesh is left clear, whilst the others 
are covered by them. At the base are an immense number of 
silken glassy hairs, which envelope it almost completely. The lid 
is of quite a different style of architecture, being an irregular 
network of stout fibres, and containing none of the micros- 
copic fibres that are so abundant in the body of the vase. 
The lash chambers exist in the wall; they are like cylinders, with 
a large opening at one end, and perforated by pores, through which 
the water is drawn by the lashes, and driven into the interior of 
the vase, whence it escapes partly by the alternate open meshes in 
