78 PLATE XXXI. 



number were much smaller. In one of them the basal 

 membrane is in a fine state of preservation. It is 

 abundantly furnished with spicula, which are not 

 arranged in a reticulation, as they are in the dermal 

 membrane, but are thickly and irregularly felted 

 together. 



Hymeniacidon fallaciosus, Boiverbmik. 



Vol. ii, p. 160, ' Mon. Brit. Spongiadse.' 



Fig. 4. — Represents the type-specimen in the collec- 

 tion of the Rev. A. M. Norman. Natural size. 



Fig. 5. — One of the stout acerate spicula of the 

 skeleton. 



Since the first publication of this species I have 

 received a small specimen of it of an irregular, massive 

 form, about half an inch in diameter. It was found 

 by my friend Mr. C. W. Peach in, I believe, Fowey 

 Harbour. I have also received five specimens in a 

 bottle from Mr. Norman, labelled " Strangford Lough, 

 tidemarks, October 8th, 1869." Among the five there 

 was one undistinguishable by its external charactei's 

 from the others, which proved, on microscopical exa- 

 mination, to be a specimen of Hijmeniacidon fallaciosvu. 

 It was parasitical on the stems of a Fucus, embracing 

 and binding four or five of the branches together into 

 a mass irregularly cylindrical in shape, about an inch 

 in length, and rather more than half an inch in dia- 

 meter. The whole of the structural characters were 

 in perfect accordance with those of the type-specimen. 



Hymeniacidon albescens, Btncninuik. 



Vol. ii, p. 161, ' Mon. Bi'it. Spongiadae.' 



Figs. 6, 7. — Specimens of the species from the 

 Guliot Caves, Sark, with the basal sponge, whence the 

 virgultose portion springs. Natural size. 



Figs. 8, 9. — Specimens from Roundham Head, 



