BRITISH SPONGIAD^E. 247 



This sponge was dredged at Shetland, in 1864, by Mr. 

 J. G. Jeffreys, and preserved for me by Mr. Peach. The 

 specimen is irregularly fan-shaped, an inch and three quar- 

 ters in height, an inch and a half at its greatest breadth, 

 and five lines greatest thickness, and it has been firmly 

 imbedded, apparently during its growth, by juxtaposition, 

 in the substance of a specimen of Halichondria inornatus ; 

 the two sponges in their present dried condition being 

 scarcely to be distinguished from each other, their colour and 

 general appearance being so much alike ; but a micro- 

 scopical examination of a small portion of either, immedi- 

 ately discriminates them, H. simplex having the spicula 

 acuate, while those of H. inornatus are spinulate. 



The organization of this species is exceedingly simple ; 

 one form, only, of spicula, prevailing through all its tissues ; 

 but the large size of those organs, the open diffuse struc- 

 ture of the skeleton reticulations, and the somewhat coarse 

 and profusely spiculous dermal membrane readily serve to 

 separate it from the nearly allied species. 



13. Halichondria subdola, Bowerbank. 



Sponge. Ramose, branching irregularly. Surface even, 

 smooth. Oscula and pores inconspicuous. Dermal 

 membrane spiculous. Spicula acuate, minute, and 

 slender, dispersed, very numerous. Skeleton. Rete 

 very delicate and slender, irregular ; spicula acuate, 

 long, and slender, variable in size. 



Colour. Dried, cream white. 



Habitat. Vazon Bay, Guernsey, Mr. Cooper. 



Examined. hi the dried state. 



This little sponge is an exceedingly deceitful subject. In 

 its present condition it looks, at first sight, much like a 

 branch broken off from a small Dictyocylindrus, but the 

 total absence of a peripheral system and of external defen- 

 sive spicula of any kind forbids our assigning it to that 



