164' A MONOGRAPH OF THE 



Dermal membrane pellucid, abundantly spiculous; 

 spicula acerate, long, and slender, dispersed. Skele- 

 ton. Spicula acerate, long, and slender, larger and 

 stouter than those of the dermal membrane. 



Colour. — Dried, milk white. 



Habitat. — Moray Firth, Rev. Walter Gregor. 



Examined. — In the dried state. 



This remarkable sponge existed in several small patches, 

 on a fragment of a dead shell of a large Pecten, about two 

 inches in length by one in breadth. There were six or 

 seven small patches, none of which exceeded three lines in 

 breadth, or about six or eight in length, and the thickness 

 did not in any one exceed that of thin writing paper. 



The dermal membrane is crowded with spicula of the 

 same form as those of the skeleton, but somewhat less in 

 length and diameter. It is difficult to trace the interstitial 

 membranes, as the sponge is so thin that it is, in truth, 

 nearly all dermal membrane, and in many places in the 

 pieces examined, there appeared to be nothing in the shape 

 of interstitial tissues between the dermal and basal mem- 

 branes. 



9.HYMENIACID0N PERARMATUS, Bowerhank. 



Sponge. Coating, thin ; surface smooth and even. Oscula 

 numerous, dispersed, slightly elevated. Pores incon- 

 spicuous. Dermal membrane pellucid, abundantly 

 spiculous ; spicula dispersed, acerate, long, and large; 

 profusely furnished with large equi-anchorate bi- and 

 tri-dentate retentive spicula. Skeleton. Spicula 

 acerate, long, and large, very abundant. Interstitial 

 membranes abundantly furnished with large bi- and 

 tri-dentate, equi-anchorate, retentive spicula; In- 

 ternal defensive spicula attenuato-clavate entirely 

 spined, large, very variable in length and size. 



Colour. — Dried, light buff yellow. 



