116 DR. J. S. BOWERBANK ON THE SPONGIAD^E. [Feb. 6, 



recurvo-ternate ones. Skeleton-spicula fusiformi-acerate, large and 

 long, and the same form long and slender. 



Colour in spirit dark dull green. 



Hab. Hammerfest, 150 fathoms (R. M' Andrew, Esq.). 



Examined iu the wet state, in spirit. 



I received this and two other species of Tethea from my friend 

 Mr. M'Andrew in 1855 as a portion of the results of his dredging 

 off the coast of Norway during that year. On examining and de- 

 scribing its structure I discovered in its dermal membrane the inter- 

 esting and beautiful elongo-stellate form of spiculum which I subse- 

 quently figured in the first part of my paper " On the Anatomy and 

 Physiology of the Spongiadee " in tbe ' Philosophical Transactions 

 of the Royal Society' for 1858, plate 25. fig. 18 ; and in the second 

 part of the paper in the Phil. Trans, for 1862 I also figured a 

 portion of the dermal membrane with the same forms of spicula in 

 situ in plate 31. figs. 14 and 15, designating the sponge from which 

 the figures were derived Tethea muricata. 



The condition of this specimen is remarkable. It has two deeply 

 incised wounds in a horizontal direction, the interior surfaces of 

 which are healed and covered by a new portion of dermal membrane. 

 The fractures are on two sides of the mass and are opposite to each 

 other, as if an attempt had been made by a fish to tear it from the 

 base on which it was seated, but, not liking the mouthful of sharp 

 spicula, had abandoned the attempt. There are also two unin- 

 jured parts of the sponge-surface opposite to each other ; the largest 

 of the two is represented in Plate V., the smaller one on the other 

 side does not exceed four lines in length. 



The hispidation of the surface of the sponge is not apparent to 

 the eye, but it is readily sensible to the touch of the finger. It is 

 produced by the expanding radii of the large bifurcating ternate 

 heads of the connecting spicula. These organs, which perform the 

 double office of connecting and external defensive spicula, are, com- 

 paratively speaking, exceedingly large : they are from ^ to A inch 

 in length, with a diameter near the head of ^4-^ inch ; and the expan- 

 sion of the ternate heads frequently exceeds T ^ part of an inch. 

 These measurements apply to fully developed spicula ; they vary 

 to a great extent in size ; and the mode and extent of the production 

 of the ternate heads are also exceedingly variable. 



There is one large terminal osculum, which appears to be perma- 

 nently open, and beneath which all the excurrent canals are concen- 

 trated. The dermal membrane and the porous system are exceedingly 

 interesting and beautiful. A small piece of the dermis is represented 

 by fig. 6, Plate V. The areas of the dermal network are not open ; 

 they are each furnished with a very transparent membrane, upon 

 which a few spicula may occasionally be seen. I could not detect 

 any open pores. The elongo-stellate spicula are exceedingly nume- 

 rous on the dermal membrane : there are also a few of them scattered 

 on the interstitial membranes near the surface of the sponge ; but they 

 are of very rare occurrence on the deeper-seated portions of those 



