134 Mr. H. J. Carter on the 



HEXACTINELLIDA. 



Family 1. VlTREOHEXACTINELLIDA. 

 Fibre vitreous spiculiferous. 



Family 2. Sarcohexactinellida. 

 Sarcospiculiferous. 



Family 3. Sarco-vitreohexactinellida. 

 Partly fibro-vitreous, partly sarcospiculiferous. 



CALCAREA*. 



Groups f. 



CERATINA. 



Family 1. Luffarida. 



Forms only a single group. 



Sarcode chiefly purple or dark red-brown throughout, 

 darkest on the surface. Skeleton composed of a uniform 

 reticulation of horny, crisp, rigid, anastomosing transparent 

 fibre, of a bright golden or brown amber-colour^:; cored 

 throughout continuously with an opaque white, granuliferous, 

 mostly tubular membrane, less in diameter than half that 

 of the fibre ; terminating by anastomosis just above the level 

 of the surface. Structure reticular. Texture hard, resistent, 

 brittle §. Forms massive, lobed, tubular, single or grouped ; 

 or branched dichotomously, branches round, solid. 



* For a classification of the Calcareous sponges, together with illustra- 

 tions, see Hiickel's monograph entitled 'Die Kalkschwamme,' 1872. 



t The characters of the groups have been deduced from descriptions 

 generally of the genera and species, which will be found in the last part 

 of this communication. 



X The colour of sponges, as before stated, is for the most part eva- 

 nescent ; it may be general or confined to the dermal sarcode, and here only 

 to those parts which are most exposed to the sun. What has been stated 

 in the Anatomy and Physiology of the Spongida as regards the specific 

 value, not only of colour, but of form, should be here remembered. 



§ Texture is not always to be depended on, as resilient or elastic fibre 

 if much bruised may become tow-like or cottony, and stiff" fibre, if the 

 specimen has not had all its salt extracted by soaking in fresh water, may, 

 on the least dampness in the air, become flaccid, like glue under similar 

 circumstances. Indeed some sponges, like certain Fungi, expand so 

 much under the influence of damp or moisture, that they appear to be 

 hygrometric. 



