182 PLATE LXXI. 



HYMENIACIDON FOLIATUS, Bowerbank. 

 Plate LXXI. 



Sponge sessile, basal portion comparatively large 

 and spreading ; elevated portion folious ; surface 

 smooth. Oscula and pores inconspicuous. Dermal 

 membrane pellucid, thin, aspiculous. Skeleton. Spi- 

 cula more or less spinulate, of nearly equal size, very 

 abundant, loosely and irregularly disposed. 



Colour. Cream white in the wet state. 



Habitat. Shetland ; Mr. C. W. Peach. 



Examined. In the wet state from spirit. 



I received a single specimen of this species with 

 several other sponges in spirit from my kind and inde- 

 fatigable friend Mr. C. W. Peach, who obtained it at 



Q 



Shetland in 1864. It is seated on a small pebble not 

 quite eight lines long by about five lines wide. The 

 basal mass of the sponge spreads comparatively to a 

 considerable extent over one end of the stone, and the 

 folious portion rises from it in the form of a thin, 

 pointed, and somewhat curved leaf-like plate, about 

 two and a half lines in greatest breadth, rather less 

 than four lines in height, and of a thickness not 

 exceeding that of a stout sheet of writing paper. It is 

 very probable that hereafter considerable modifications 

 both as regards size and form may be found to exist in 

 this species, but as far as we can see at present it 

 cannot, by its structural peculiarities, be referred to 

 any of the British Hymeuiacidons with spinulate 

 spicula with which we are acquainted. 



The sponge though so small is apparently not in an 

 early stage of development ; as there are, in the small 

 piece removed for microscopical examination, not ex- 

 ceeding two lines in diameter, six foraminiferous shells, 

 some of them containing their own animal matter, and 

 there are others observable in the folious portion of 

 the sponge. 



I could not detect oscula or pores either on the piece 



