228 

 * 

 of horny fibre with a core of proper spicules. Form of spicnle. chiefly 

 simple acerate and chieUy confined to the interior of the fibre. 



Farn. 1. Chalinida. Digitations solid, vertical or procumbent. 

 (4 Gruppen.) 



Fam. 2. Cavochalinida. Tubulär, vasiform, aculeated patu- 

 lous, or compressed flabellately; plane and frondose or dactyloid. 

 (7 Gruppen.) 



Fam. 3. Acervochalinida. Massive clalhrous, or compact 

 and isodactyal. (3 Gruppen.) 



Fam. 4. Pseudochalinida. Digitiferous, composed of fibre cored 

 with proper spicules and foreign bodies. (2 Gruppen.) 



Ordo V. Echinonemata. Possessing a sceleton composed of 

 horny fibre cored with proper spicules internally and echinated with 

 proper spicules externally. 



Fam. t. Ectyonida. Echinated with proper spicules on the 

 fibre (5 Gruppen). 



Fam. 2. Axinellida. Echinated with proper spicules projec- 

 ting from the interior of the fibre. (2 Gruppen.) 



Ordo VI. Holorhaphidat a. Possessing a sceleton whose fibre 

 is almost cntirely composed of proper spicules bound together by 

 a minimum of sarcode. Form of spicules variable. 



Fam, 1. Renierida. Spicules more or less arranged in a 

 fibrous form. Structure yielding to pressure like crumb of bread. 

 (9 Gruppen.) 



Fam. 2. Suberitida. Tissue chiefly cork-like; spicules mat- 

 ted feit -like, cancellous and crushable, or radiated compact and 

 hard; spicule chiefly pin-like, with the sharp ends projecting from 

 the surface velvet-like. (4 Gruppen.) 



Fam. 3. Pachytragida. More or less corticate, with a can- 

 cellous. more or less radiated structure, internally well difl:erentiated. 

 (3 Gruppen). 



Farn. 4. Pachastrellida. Without cortex; densely spiculi- 

 ferous, even to stony hardness (Lithistina). Structure coufused; 

 no fibre (2 Gruppen). 



Fam. 5. Potamospongida. Fragile sponges beariug seed- 

 like bodies or statoblasts, and inhabiting fresh water. 



Ordo VII. Hexactinellida. Possessing a sceleton charged with 

 proper spicules. Spicules all based on a sexradiate type, as indi- 

 cated by their forms and the presence of a sexradiate cross at the 

 centre of the spicular canal. 



Fam. 1. Vitrohexactinellida. Fibre vitreous spiculiferous. 

 (3 Gruppen.) 



Fam. 2. Sarcohexactinellida. Sarcospiculiferous. (2 Gruppen.) 



