236 PLATE XLVII. 



disposition of tlie fasciculi in tlie skeletons is, as if they 

 had been thrown carelessly together in every possible 

 diagonal direction, the interstices of the skeleton form- 

 ing elongated angular areas, like those of a confused 

 mass of netting extended in one direction only. The 

 fasciculi in the type-specimen are large and long, each 

 consisting of many more spicula than it is possible to 

 count. The bundles are usually independent of each 

 other, but occasionally they are connected laterally by 

 the offset of a few spicula on a slender l3undle running 

 from the one to the other. The general connection is 

 by the intermixture of their terminal radial spicula, or 

 by single spicula disposed at nearly right angles to the 

 p-eneral direction of the skeleton fasciculi. 



There are but three genera with which this one is at 

 all likely to be confounded, and these are Halichondria, 

 Hymedesmia and Desmacidon. Eaphiodesma diflfers 

 from Halichondria by the distinctly and compactly 

 fasciculated structure of the reticulation, and by the 

 apparent disconnection of the parts of the rete. It also 

 differs from Hymedesmia, by the fasciculi always form- 

 ing a connected though disjointed network ; while in 

 the last-named genus the fasciculi are normally separate. 

 The compactly fibrous structure of the middle portions 

 of the fasciculi of Raj^hiodesma simulate verjr closely 

 the structure of the truly continuous fibre of a Desma- 

 cidon, but their universal want of continuity distinctly 

 characterises them as fasciculi and not multispiculous 

 keratose fibre. Figure 8, Plate XLA^I, represents a 

 portion of the skeleton of B. lingua exhibiting the form 

 and arrangement of the faggot-like bundles of which it 

 is composed, from the specimen represented in Plate 

 LXXVII, fig. 1. 



