o A MONOGRAPH OF THE 



Type, HymerapUa stellifera, Bowerbank. Vol. I, Plate 



XXXIV, Fig. 370. 



14. Htmedesmia, Bowerbank. 



Skeleton. A common basal membrane sustaining a thin 

 stratum of disjoined fasciculi of spicula. Vol. I, 

 p. 190. 



Type, Hymedesmia Zetlandica, Bowerbank. Vol. I, Plate 



XXXV, Pig. 371, and Plate XVIII, Pig. 296. 



Suborder II. Spiculo-membranous skeletons. Composed 

 of interstitial membranes, having the skeleton spicula 

 irregularly dispersed on their surfaces. 



The prominent character of this Order is that the 

 spicula of the sponges composing it do not assume either 

 the radiate, fasciculate, or reticulate structural arrangement. 

 The distribution of the spicula on the interstitial mem- 

 branes being without any approximation to order. 



Hymeniacidon, Bowerbank. 



Skeleton without fibre, spicula without order, imbedded in 

 irregularly disposed membranous structure. Vol. I, 

 p. 191. 



Type, Hymeniacidon caruncula, Bowerbank. Vol. I, Plate 

 XXXV, Pig. 372. 



Suborder III. Spiculo-reticulate skeletons. Skeletons 

 continuously reticulate in structure, but not fibrous. 



1. Halichondria. 



2. Hyalonema. 



3. Isodictya. 



4. Spongilla. 



