772 DR. J. S. BOWERBANK ON THE SPONGTADJE. [Nov. 21, 



punctiunculate, abundantly furnished with subfusiformi-spinulate 

 spicula, radiating irregularly from the centres to the circumferences 

 of the branches ; spicula very irregular in length. 



Colour, in the dried state, red. 



Hab. Sharks' Bay, Western Australia. 



Examined in the dried state. 



I obtained this interesting species from a dealer in natural-history 

 specimens. It is 9 inches in height aud 7 inches in greatest breadth. 

 Its mode of growth is very singular. It consists of a number of 

 separate irregularly shaped fan -like aggregations, by anastomosis of 

 the smaller branches, all projected in nearly the same plane, the 

 whole forming a complicated fan-shaped mass of branches, from 

 many of which, in numerous parts, by a careful examination, minute 

 leaves of fuci may be seen projected ; but whether these are separate 

 and independent growths, or projections from an originally enveloped 

 fucus, it is difficult to decide, as I could not trace any portions of 

 the stem of a fucus in numerous sections made at right angles to the 

 surface of the sponge, even when mounted in Canada balsam. From 

 the very young condition of all these minute fuci, and there being 

 two species of them, and several other parasitical bodies, such as 

 little Barnacles, embedded in some of the branches, I am inclined 

 to believe the small fuci to be parasites on the sponge, and not the 

 sponge on a fucus. 



The dermal surface is furnished with an irregular fibro-reticulate 

 rete, the fibre of which does not appear to be so profusely furnished 

 with spicula as those of the skeleton. The minute hispidation of the 

 surface is produced by the projection of the spicula of the fibres of 

 both the dermal rete and the skeleton immediately beneath it. This 

 character is not visible, excepting in thin slices of the sponge made 

 at right angles to the dermal surface when mounted in Canada 

 balsam. The fibres of both the surface and the skeleton are very 

 remarkable ; their surfaces are profusely punctiunculated ; this 

 character is best seen in the fibres of the dermal rete, the surfaces 

 of which are usually less abundantly spiculous than those of the 

 skeleton. These minute dottings of the surfaces of the fibres require 

 a power of not less than 300 linear, when sections of the sponge are 

 mounted in Canada balsam, to render them distinctly to the eye. 

 I have never seen this remarkable dotting of the surface of the 

 fibres of a keratose sponge in any other species of sponge ; and in 

 the one in course of description it forms a very decisive specific 

 character. 



The structure of the skeleton is very irregular and complicated. 

 The fibres are stout and rigid, and are profusely furnished with their 

 defensive spicula. These organs vary to great extent in their length 

 and diameter ; one of the largest measured ^ inch in length, while 

 one of the numerous short ones measured only ^J inch in length ; 

 the two forms are distributed on the fibres without the slightest 

 approach to order. This sponge is a very remarkable species of the 

 genus. It is unlike any of its numerous congeners. 



