BRITISH SPONGIADiE. 149 



Genus Hymedesmia, Bowerbank. 



Section * * Skeleton spicula acuate. 



1. Hymedesmia radiafa, Bowerbank. 



Section * * * Skeleton spicula spinulate. 



2. Hymedesmia stellata, Bowerbank. 



Section * * * * Skeleton spicula cylindrical. 



3. Hymedesmia Zetlandica, Bowerbank. 



1. Hymedesmia hadiata, Bowerbank. 



Sponge. Coating, very thin, surface even, smooth. Oscula 

 simple, dispersed. Pores inconspicuous. Dermal 

 membrane aspiculous, pellucid. Skeleton composed 

 of numerous widely-radiating groups of long and 

 slender attenuato-acerate spicula; groups irregularly 

 dispersed ; and also exceedingly large and long acuate 

 or sub-clavated acuate spicula, irregularly dispersed 

 amidst the skeleton tissues. Internal defensive spicula 

 clavated attenuato-acuate, incipiently entirely spined, 

 stout and variable in length, very numerous. 



Colour. Dried, light greenish-gray. 

 Habitat. Shetland, Mr. C. W. Peach. 

 Examined. In the dried state. 



I am indebted to my friend Mr. Peach for this specimen, 

 the first of the species I have seen. It coats very thinly a 

 space on the surface of a fragment of a granite boulder, of 

 about an average of two inches in diameter. It was dredged 

 at Shetland, by Mr. J. G. Jeffreys, in 1864, and was pie- 

 served for me by Mr. Peach, who accompanied the expe- 



