BRITISH SPONGIAD^. 269 



not exceeding two and a half lines in length by one in 

 breadth, and it looks exceedingly like a stain of thin white- 

 wash on the margin of the shell which does not exceed five 

 lines in length. None of the oscula were open, but their 

 situation was well indicated by a concentration of the 

 dermal spicula in a radial form at particular spots on the 

 dermal membrane, in all other parts of which the spicula 

 were irregularly but equally dispersed. The tension spi- 

 cula of the dermal and interstitial membranes are remark- 

 ably large and stout as compared with those of the skeleton, 

 which although much longer, are not above half the dia- 

 meter of the dermal ones. The skeleton in the portion 

 examined formed but a very small part of the sponge, and 

 was represented by a few straggling fascicuU of spicula ; 

 the sponge being, in truth, mainly composed of dermal and 

 a few very shallow interstitial membranes with a very thin 

 layer of skeleton fasciculi, the thickness of the whole being 

 less than that of writing paper. 



From the paucity of the skeleton in this specimen it is 

 probable that the sponge is not an adult, and that when 

 fully developed the reticulated skeleton would be more 

 abundant. 



I am indebted to the kindness of my late friend Mr. 

 Barlee for this singular and uiteresting little species. He 

 dredged it in deep water at Shetland. 



27. Halichondria farinaria, Bowerhanh. 



Sponge. Coating, thin ; surface smooth and even. Os- 

 cula numerous, simple, minute, dispersed. Pores in- 

 conspicuous. Dermal membrane pellucid, furnished 

 abundantly with slender spinulate spicula, and more 

 sparingly with small inflato-cylindrical tension spicula. 

 Skeleton rete slender, areas irregular, open, and dif- 

 fuse ; spicula spinulate, small, and slender. 



Colour. — Living, deep orange or scarlet. Dried, ochreous 

 yellow. 



