CHAPTER III 



SPONGES ^ 



PHYLUM POKIFERA. 



CLASS I. CALCAREA (CALCISPOXGIAE). 



Grade 1. Homocoela. 

 „ 2. Heterocoela. 



CLASS IL HEXACTINELLIDA (HYALOSPONGIAE). 



Order 1. Lyssacina. 

 „ 2. Dictyonina. 



CLASS HL DEM0SP0NGL4E. 



Grade 1. Tetraxonida. 

 Order L Camosa. 

 „ 2. Tetractinellida. 



Grade 2. Moxaxonida. 

 Order 1. Halichondrina. 

 „ 2. Hadromerina. 



Grade 3. Keratosa. 

 Order 1. Dictyoceratina. 

 „ 2. Dendroceratina. 



Grade 4. Myxospongida. 

 (No Orders.) 



I. Introduction. 



The Sponges or Porifera form a well -characterised group of 

 animals, very abundant in all seas, from the equator to the poles, 

 and flourishing at all depths, from the shore-line to the profoundest 

 abysses. One family (or sub-famil}'), and, so far as is known, one 

 only — the SpongiUinae — has established itself in fresh water, and is 

 represented by a great variety of genera and species in all parts of 

 ^ By E. A. Minchiu, M.A., Professor of Zoology, University College. Loiulou. 



