Classification of the Spongida. 



Order III. PSAMMONEMATA. 



Fi<?. 2. 



129 



Fibre of Psammonemata : a, horny sheath of vertical or large fibre ; 

 b, core ; c c, horizontal, lateral, or small fibre*. 



Possessing a skeleton composed of solid fibre more or less 

 cored f with foreign bodies. 



Order IV. RHAPHIDONEMATA. 



Fia-. 3. 



Fibre of Raphidonemata : a, horny sheath of vertical or large fibre ; 

 b, core ; c c, horizontal or small fibre. 



Possessing a skeleton composed of horny fibre with a core 

 of " proper spicules." Form of spicule chiefly simple acerate, 

 and chiefly confined to the interior of the fibre. 



* To show that the general outline of the fibrous structure is the same 

 in the Orders 3, 4, 5, and 6, all the figures (viz. 2 to 5 inclusive) will be 

 observed to be alike, differing only in the accessories. Thus by referring 

 to the most simple one, viz. fig. 2, the rest will be easily understood. 



t The substantive "core " is here used verbally for brevity. 

 Ann. & Mag. N. Hist. Ser. 4. Vol. xvi. 9 



