376 MANUAL OF NATURAL HISTORY. 



II. ORDER. SILICEOUS-SPONGES (Silicea). 



Body more or less rigid or friable, and strength- 

 ened with siliceous spicula. 



1. FAMILY. Thethyan-Sponges (Thethyidse). Body 

 irregular, tuberiform, sarcoid, firm; spicula 

 fasciculate, and diverging from the centre to 

 the circumference. 



III. ORDER. CALCAREOUS-SPONGES (Calcarea). 



Body not very soft, composed of a sub-cartilagin- 

 ous substance, supported by calcareous spicula. 

 1. FAMILY. Grantian-Sponges (Grantiidae). Body 

 more or less solid, irregular, traversed by 

 tortuous canals, terminating by oscula over 

 the whole surface. 



In finally revising the divisions of the Animal 

 Kingdom, we considered it advisable to alter 

 somewhat the arrangement as given at page 4 

 We have therefore subjoined the order which we 

 have adopted in the preceding pages, in which, 

 instead of endeavouring to approximate connecting 

 links between the different Sub-kingdoms, we have 

 placed the Classes of the five primary divisions in 

 linear, graduated series, commencing in each with 

 the most highly developed. Several additional 

 synonymes have also been added for the sake of 

 reference. 



