LIME-SPONGES—CARNEOSPONGLA, 13 
way the Ascetta feeds. 
Other sponges differ from it in 
having a shapeless form, many large outlets instead of 
one, and numerous sacs lined with ciliated cells. 
Development.—The young are at first free swimmers, 
being produced from eggs, 
escaping into the water as 
oblong little creatures, with 
numerous cilia, V. They 
soon become attached to 
the bottom, spicules appear, 
and they gradually assume 
the parent form. 
Order I. Lime-Spon- 
ges (Calcispongig),—In 
these, the spicules are made 
of lime, and the canals lined 
with ciliated cells. They 
are few in number, and may 
be represented by the little 
white sponge, Sycon ciliatum, 
and Ascetta primordialis 
(Fig. 112). 
Order IJ. Carneo- 
spongiz.— The spicules 
of these forms are either 
fibrous and horny, or sili- 
cious, and the ciliated cells 
are only found in little 
cavities, or stomachs. To 
this order belong a host of 
beautiful forms: the com- 
mon sponges of commerce, 
the fresh-water Spongilla, 
Fic. 12,—Skeleton of Zuplectella - 
speciosa. 
the wondrous Holtenia, and the Lupleciella, or Venus's 
" flower-basket (Fig. 12). 
