DESMACIDON. 177 



from a small specimen an inch in height and about 

 three-fourths of an inch in breadth. Since then I 

 have received a much better developed specimen for 

 examination from my friend Mr. T. Higgin, of Huyton, 

 near Liverpool, who obtained it at Guernsey. This 

 specimen is irregularly ramified in nearly the same 

 plane. It is four inches and a quarter in height from 

 its present base, its natural attachment not being 

 present. The basal portion of the stem does not 

 exceed in height that of the type specimen; imme- 

 diately above its base it divides into three branches, 

 each of which is about the same diameter as at the 

 basal portion; two of the branches are short, but 

 the third is two inches and a half in height, and it 

 terminates by dividing into several branchlets, thus 

 attaining a total height of four inches and a quarter. 

 All the larger branches are fistulous, the central 

 cavities being large, and the parieties comparatively 

 thin ; and one short branch near the base has an open 

 termination. 



" This specimen agrees very closely with the type 

 in all its structural characters, but the more fully 

 developed state of its growth requires an emendation 

 of the specific characters derived from its external 

 form, and I therefore propose the following to replace 

 the one in Vol. Ill, p. 312 : 



"Sponge. Branching irregularly; branches fistu- 

 lous, parieties thin. Surface rough, ragged, and 

 open. Oscula unknown. Pores dispersed. Dermal 

 membrane rather sparingly spiculous ; spicula acuate, 

 slender, same length as those of the skeleton. 

 Skeleton-rete very open, fibre compact but rather 

 slender ; spicula acuate, short and stout. Interstitial 



VOL. IV. 12 



