LIME-SPONGES. CAR 



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 

 Dblong 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 ( Cahispongia] . 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. n). 



Order .II. Carneo- 

 Spongise. 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, 



the wondrous Holtenia, and the Euplectella, or Venus's 

 flower-basket (Fig. 12). 



FIG. 12. Skeleton of Euplectella 

 speciosa. 



