152 A MONOGRAPH OF THE 



3. Hymedesmia Zeilandica, Bowerbank. 



Sponge. Coating very thin ; surface smooth and even. 

 Oscula simple, dispersed. Pores inconspicuous. Der- 

 mal membrane pellucid, aspiculous. Skeleton : spicula 

 sub-biclavated, cylindrical, numerously fasciculated, 

 rather large, of nearly uniform size and proportions. 

 Internal defensive spicula attenuato-acuate, entirely 

 and strongly spined ; large and stout, rather numerous ; 

 spines conical, acute, often recurvate. Retentive spicula 

 bidentate and tridentate equi-anchorate, ratlier stout 

 and numerous, dispersed ; and simple bihamate, large, 

 but very slender, fasciculated, fasciculi numerous, 

 dispersed. 



Colour. Dried, buff yellow. 



Habitat. Deep sea, Shetland, Mr. Barlee. 



Examined. In the dried state. 



I am indebted to my indefatigable friend Mr. Barlee for 

 this sponge. He obtained it in the course of his deep-sea 

 dredging at Shetland, in 1858. There are two small 

 patches of it on the front margin of a valve of Docinia 

 eccolita, one on the outer and the other on the inner surface 

 of the shell ; neither of them exceed a quarter of an inch 

 in diameter. I have also three other small specimens of it 

 of similar dimensions, on the two sides of a flat pebble 

 about three fourths of an inch in diameter, from the same 

 locality. One of them is in juxtaposition with a specimen 

 of Hymeraphia vermiculata, from which it may be readily 

 distinguished by a lens of an inch focus, by its smooth 

 surface, and by the total absence of large external defensive 

 spicula. I could not detect the oscula without the aid of a 

 microscopic power of about 100 linear, and by direct light. 

 They were few in number, and very small. The spicula in 

 the fasciculi of the skeleton are very numerous. The 

 bundles are dispersed irregularly in all parts of the sponge, 



