Classification of the Spongida. 135 



Family 2. Aplysinida. 



Forms only a single group. 



Sarcode colourless, black-purple or madder-brown through- 

 out, darkest on the surface. Skeleton composed of an irregular 

 reticulation of subrigid or flaccid, horny, anastomosing translu- 

 cent fibre, of a dark amber-colour ; cored interruptedly hei*e and 

 there with a granuliferous tubular membrane, much more than 

 half the diameter of the fibre in width, and presenting here and 

 there a fragment or two of foreign objects. Fibre of two 

 kinds, viz. vertical or large, and horizontal* or small fibre, 

 the former terminating on the surface in small points or whip- 

 like filaments. Structure reticular. Texture soft, resilient. 

 Forms incrusting, or massive, or tubular, or flabellate, or folia- 

 ceous, sometimes proliferous. 



Family 3. Pseudoceratida. 



Forms only a single group. 



Sarcode madder-brown or brownish yellow throughout. Ske- 

 leton mostly the same as in the Aplysinida. Vertical fibre ter- 

 minating on the surface in whip-like filaments among a crust of 

 foreign bodies, or in a dermal reticulation of horny fibre charged 

 with " proper spicules." Structure reticular. Texture resi- 

 lient and open, or soft and compact. Forms massive, lobed, 

 or rising into a group of tubular digitations. 



PSAMMONEMATAf. 



Family 1. Bibulida. 



Group 1. Euspongiosa. 

 Sarcode black, purple, or brown externally, pale amber 

 within. Skeleton composed of a reticulation of solid, horny, 



* The term " horizontal " here must be considered equal to " lateral," 

 as the main or vertical fibre often assumes a radiating or plumose form, in 

 which its direction may become horizontal. 



t The collection of sponges in the British Museum, which has chiefly 

 served to form the families of this order, came from all parts of the 

 world, where, from their consisting for the most part exclusively of the 

 skeleton, they have apparently been picked up on beaches, having pro- 

 bably, from their great size, originally grown in deep-sea caverns, from 

 which they could not have been obtained in any other way. Hence 

 their mostly unsatisfactory state for this purpose. 



The principle in arrangement has been to begin with horny fibre 

 sparingly cored with foreign bodies, then to go to that in which the 

 core is more general, and finally to end with that in which the horny 

 element is scarcely visible, and the core of foreign bodies only held to- 

 gether by a minimum of sarcode, like the spicules in the Holorhaphidota. 



The family " Pseudohircinida " has been added for such species of 

 the Psammonemata as have " proper spicules " in addition to the core 

 of foreign objects. 



